Why Grind Size Matters

Of every variable you can control when brewing coffee — dose, water temperature, brew time, agitation, ratio — grind size has the single largest impact on what ends up in your cup. That is not an opinion; it is a direct consequence of physics. When you grind a coffee bean, you are fracturing it into smaller pieces, and each fracture exposes new surface area to the water. The more surface area you expose, the faster the water can dissolve the soluble compounds inside the bean. Grind size is, in effect, a dial that controls the rate of extraction. Turn it one way and extraction speeds up; turn it the other and it slows down. Every other variable — temperature, time, turbulence — is constrained by the surface area you create at the grinder.

To understand why this dial matters so much, you have to understand what extraction actually is. Hot water dissolves compounds from the coffee cell structure in a predictable order: acids and salts come out first, then sugars, then the heavier bitter compounds and astringent tannins. This is why a properly extracted cup tastes balanced — the acids give it brightness, the sugars give it body and sweetness, and the bitter compounds provide structure without dominating. When you grind too fine for a given brew method, the water extracts too much too quickly, pulling those late-stage bitter compounds into the cup before you can stop the brew. When you grind too coarse, the water passes through without dissolving enough, and you are left with a thin, sour, underdeveloped drink. The grind size is what lets you time the extraction so that you stop the brew in that sweet spot where the desirable compounds are in the cup and the undesirable ones are not.

Think about the math for a moment. A whole coffee bean has a fixed surface area. Break it in half and you roughly double the surface area while keeping the volume constant. Break it into a thousand pieces and you increase the surface area by roughly a factor of ten. This is why a fine grind extracts in twenty-five seconds under espresso pressure while a coarse grind needs four full minutes of immersion in a French Press — the fine grind has dramatically more surface area for the water to work on. The relationship is not linear; it is geometric. Small changes in particle size produce large changes in extraction rate, which is why a half-turn adjustment on a burr grinder can move a coffee from balanced to bitter.

This is also why grind size is the variable you should change first when something tastes off. If your pour over is consistently sour and you respond by adding more coffee, you are fighting the symptom rather than the cause. If your espresso is bitter and you respond by pulling a shorter shot, you are again treating the symptom. The root cause in both cases is almost certainly that the grind is wrong for the brew time and method. Dialing in the grind first means every other variable — dose, temperature, ratio — is working against a stable extraction rate. Once the grind is right, small tweaks to the other variables become meaningful and predictable instead of random.

There is also a practical reason grind size deserves your attention before anything else: it is the one variable that a cheap or worn-out grinder can sabotage without you knowing. A blade grinder does not produce particles of a consistent size — it smashes beans into a mixture of dust and chunks. That means even if your dose, ratio, and time are perfect, the extraction will be uneven because the fine particles over-extract while the coarse particles under-extract simultaneously, in the same cup. You cannot fix that by adjusting brew time; you can only fix it by using a better grinder. This is why the coffee world repeats the same advice to anyone who will listen: buy a burr grinder before you buy a better coffee maker. The grinder is the bottleneck. Get the particle size right and consistent, and the rest of the brewing process becomes tractable.

The guide below walks through the specific grind size for each major brewing method, explains why each size works for that method's brew time and pressure, and then covers the science of extraction, how to troubleshoot by taste, and how to store your coffee so that the grind you carefully dialed in actually produces the cup you intended.

Grind Size by Brewing Method

Different brewing methods expose coffee to water for different lengths of time and under different amounts of pressure. A French Press steeps coffee for four minutes at zero pressure; an espresso machine forces water through a puck at nine bars of pressure in twenty-five seconds; a cold brew sits in room-temperature water for twelve to eighteen hours. Because the extraction rate depends on how long the water has to work and how hard it is being pushed, the correct grind size is different for each method. The principle is simple: short contact time and high pressure need a fine grind to expose enough surface area quickly; long contact time and no pressure need a coarse grind so the extraction does not run away and over-extract.

The visual references below — sea salt, table salt, powdered sugar, flour — are not decorative. They are the standard shorthand that baristas and coffee educators use because they are things you can actually find in a kitchen and compare against your grind. Hold a pinch of your ground coffee next to a pinch of the reference substance and look at them side by side. The goal is to get the particle size in the same ballpark, not to achieve a perfect match. Your grinder's settings and your beans' density will vary, so treat these as starting points and dial in by taste.

• French Press — Coarse

  Like sea salt

  The French Press is a full-immersion brewer: the coffee steeps in the same water for the entire brew, typically four minutes. Because the water sits with the coffee for so long, a fine grind would expose too much surface area and the brew would over-extract, pulling bitter, astringent compounds into the cup long before you plunged. A coarse grind — particles about the size of coarse sea salt, roughly 0.8 to 1.0 millimeters — slows the extraction down so that at the four-minute mark you are stopping the brew while it is still in the balanced zone. The metal mesh filter of a French Press also lets through more oils and fine particles than a paper filter, which contributes to the characteristic heavy body. If the grind is too fine, those fines slip through the mesh and make the cup muddy and bitter. Coarse is not a suggestion here; it is a requirement of the method's long contact time.

• Pour Over — Medium-Fine

  Like table salt

  A pour over — whether a V60, Kalita Wave, or Melitta — is a percolation brew: water passes through the coffee bed once, over the course of roughly two and a half to three and a half minutes. Because the contact time is shorter than a French Press and the water is moving rather than sitting, you need a finer grind to extract enough in that window. The target is medium-fine, roughly the size of table salt, around 0.4 to 0.6 millimeters. The paper filter catches fines and oils, so you can afford a slightly finer grind without the muddiness that plagues a French Press. The risk with pour over is channeling — water finding a path of least resistance through the bed and bypassing most of the coffee — so the grind needs to be fine enough to create some resistance in the bed but not so fine that it stalls the flow entirely.

• AeroPress — Fine to Medium

  Like fine table salt

  The AeroPress is the most forgiving brewer on this list, which is why it is so beloved by travelers and beginners. Brew time is short — typically one to two minutes of immersion followed by a quick press — and the paper filter removes fines. Because of the short contact time and the mild pressure of hand-pressing, a medium to medium-fine grind works well: around the size of fine table salt, 0.3 to 0.5 millimeters. The AeroPress is versatile enough that you can run it as a pseudo-espresso with a very fine grind and a one-minute steep, or as a longer-immersion brew closer to French Press with a coarser grind. For a standard recipe, start at medium-fine and adjust from there. The short brew time is what allows a finer grind than a French Press without over-extracting.

• Chemex — Medium-Coarse

  Like rough sea salt

  The Chemex uses a thick paper filter that is 20 to 30 percent heavier than standard pour over filters, which slows the flow of water through the bed. This means a Chemex brew takes longer than a V60 — often four minutes or more — so you need a slightly coarser grind to avoid over-extracting in that extended contact time. Target medium-coarse, just a touch finer than a French Press, around 0.6 to 0.8 millimeters. The thick filter also strips out more oils and fines, which is why a Chemex cup is famously clean and bright. If you grind as fine as you would for a V60, the thick filter will stall the drawdown and the brew will over-extract and taste muddy. Coarser is the answer here because of the filter's resistance.

• Moka Pot — Fine

  Like fine table salt

  A Moka Pot sits between a pour over and an espresso machine. Steam pressure from boiling water in the lower chamber forces water up through the coffee basket, but at a much lower pressure than a true espresso machine — typically 1.5 to 3 bars, not 9. The brew time is short, around one to two minutes of active flow, and there is no paper filter. You want a fine grind, roughly the size of fine table salt, 0.3 to 0.4 millimeters. Too coarse and the water rushes through and the coffee is weak and sour; too fine and the basket clogs, the pressure builds, and you risk a bitter, over-extracted cup — or worse, a sputtering mess. The Moka Pot cannot generate enough pressure to truly espresso-extract a very fine grind, so you aim for fine-but-not-powder.

• Cold Brew — Coarse

  Like rough sea salt

  Cold brew steeps coffee in cold or room-temperature water for 12 to 18 hours. Cold water extracts much more slowly than hot water — roughly five to ten times more slowly — so you might assume a fine grind would compensate. But the contact time is so long (a full 12 to 18 hours) that a fine grind would massively over-extract and produce a bitter, muddy concentrate. A coarse grind, similar to French Press or slightly coarser, is correct: the long steep compensates for the cold water's low extraction rate, and the coarse grind keeps the extraction from running away. The result is a smooth, low-acid concentrate. Use a coarse grind and a high ratio — typically 1:4 to 1:8 coffee to water for a concentrate — and dilute to taste.

• Espresso — Extra-Fine

  Like powdered sugar

  Espresso is the most demanding brew method because it compresses extraction into roughly 25 seconds. To extract enough in that window, you need maximum surface area, which means a very fine grind — around the size of powdered sugar, 0.1 to 0.3 millimeters. The 9 bars of pressure from the machine force water through a tightly packed puck of this fine coffee, and the resistance of the puck is what creates the extraction. If the grind is too coarse, the water passes through in five seconds and the shot is sour and thin; if too fine, the puck stalls and the shot is bitter and over-extracted, or nothing comes through at all. Espresso is also the most sensitive to grind adjustments — a single notch on the grinder can change a shot from 20 seconds to 35 seconds, and that difference is the difference between a great shot and a bad one. This is why espresso demands a stepless or finely-stepped grinder.

• Turkish — Powder-Fine

  Like flour

  Turkish coffee is the oldest brewing method still in common use, and it demands the finest grind of any method. The coffee is boiled in a cezve (a small long-handled pot) with water and often sugar, and the grounds are meant to settle in the cup and be consumed with the coffee. Because the coffee is not filtered at all and the brew is effectively an immersion with repeated heating, the grind must be as fine as flour — below 0.1 millimeters — so that it both extracts fully in the short brew time and settles slowly enough to leave a drinkable cup rather than a gritty one. This grind is finer than espresso and requires a specialized grinder; most home burr grinders cannot go this fine. Traditional Turkish grinders use conical burrs designed specifically for this powder-fine output.

• Automatic Drip — Medium

  Like sand

  A standard automatic drip coffee maker heats water and sprays it over a bed of coffee in a paper filter, with a total brew time of roughly 4 to 6 minutes. The contact time is moderate, the pressure is just gravity, and the paper filter removes fines. The correct grind is medium — roughly the size of plain sand, 0.5 to 0.7 millimeters, between table salt and sea salt. Most home drip machines are not very precise about water temperature or spray pattern, so a medium grind is forgiving and works across a range of machines. If you have a high-end drip maker like a Moccamaster that hits proper temperature and distributes water evenly, you can go slightly finer; with a cheap machine that underheats the water, a slightly coarser grind compensates for the weak extraction.

Blade Grinders vs. Burr Grinders

If you take one piece of equipment advice from this entire guide, let it be this: use a burr grinder, not a blade grinder. The difference is not a matter of preference or snobbery; it is a matter of physics, and the physics has a direct, measurable effect on the taste of your coffee. A blade grinder and a burr grinder produce fundamentally different particle distributions, and that distribution is what determines whether your extraction is even or a chaotic mix of over- and under-extraction happening simultaneously in the same cup.

A blade grinder works like a blender: a set of metal blades spins at high speed and smashes the beans into smaller and smaller pieces. The problem is that the blades hit the beans at random — a bean near the edge gets shattered immediately, a bean in the center might not be touched until later, and the already-shattered pieces keep getting hit and reduced to dust. The result is what coffee scientists call a bimodal particle distribution: a large number of particles at roughly the target size, plus a significant tail of very fine particles (fines) and a smaller tail of larger particles (boulders). You set the grinder for "medium" and you get some medium, some dust, and some chunks — all in the same batch. When you brew that mix, the fines over-extract immediately, releasing bitter compounds, while the boulders under-extract, leaving sour, acidic flavors. The cup is simultaneously bitter and sour in a way that no adjustment to brew time can fix, because you are brewing a distribution, not a single size.

A burr grinder works completely differently. Two burrs — either flat or conical — are set a precise distance apart, and the beans are fed between them. Each bean is crushed once, to a size determined by the gap between the burrs, and then exits the grinding chamber. A well-designed burr grinder produces a much narrower particle distribution — most of the particles are close to the target size, with far fewer fines and boulders. This means that when you brew, the extraction is even across the bed: all the particles are extracting at roughly the same rate, so you can stop the brew at the right moment and get a balanced cup. The narrower the distribution, the more control you have over the extraction, and the more your adjustments to brew time and ratio actually translate into predictable changes in the cup.

The practical consequence is that a burr grinder lets you dial in a coffee and reproduce that result day after day. A blade grinder makes every cup a roll of the dice — even if you run it for the same number of seconds, the particle distribution shifts because the blade hits different beans differently each time. For someone who just wants a decent cup of coffee without thinking about it, the inconsistency of a blade grinder is the single biggest barrier to improvement. You can spend five hundred dollars on an espresso machine and sabotage every shot with a thirty-dollar blade grinder.

Fortunately, a good entry-level burr grinder is not expensive. The Baratza Encore, at roughly $150, is the standard recommendation for a first burr grinder and has been for years. It uses conical steel burrs, has 40 steps of adjustment, and produces a consistent enough grind for pour over, drip, French Press, and AeroPress. It is not ideal for espresso — the steps are too coarse and the burr speed is a bit high for a true espresso grind — but for everything else it is excellent value. If you want to spend less, a hand grinder like the 1ZPresso J-Ultra (around $100) or the Timemore Chestnut C2 (around $80) uses the same type of conical burrs and produces a grind quality comparable to electric grinders at twice the price, at the cost of thirty seconds of manual cranking per cup. For espresso specifically, you need a grinder with finer steps and a more robust burr set — the Baratza Sette 270 (around $400) or the Eureka Mignon Specialita (around $400) are common entry points, and hand grinders like the 1ZPresso J-Max (around $200) also work for espresso.

One more note: even a burr grinder needs maintenance. The burrs wear down over time, especially if you grind a lot of dark roasts (which are more brittle and produce more fines, and the oils can coat the burrs). Clean your burrs every few months with grinder cleaning pellets or by grinding a small amount of white rice, and expect to replace steel burrs every few years if you grind daily. Dull burrs produce a wider particle distribution and a worse cup, which is why a "good grinder" does not stay good forever without care.

How Grind Affects Extraction and Flavor

Extraction is the process of dissolving soluble compounds out of the coffee grounds and into the water. The goal of brewing is to extract the right amount of the right compounds — enough to produce a balanced, flavorful cup, but not so much that you pull in the bitter, astringent compounds that come out last. The specialty coffee industry has spent decades studying this, and the consensus is that the ideal extraction yield — the percentage of the coffee's mass that ends up dissolved in the cup — falls in a window of roughly 18 to 22 percent. Below 18 percent and the cup is under-extracted: sour, thin, lacking sweetness. Above 22 percent and it is over-extracted: bitter, astringent, hollow. Grind size is the primary lever that moves you into, above, or below that window.

Here is the mechanism. When water contacts a coffee particle, it dissolves compounds from the outer surface inward. The finer the particle, the higher the ratio of surface area to volume, and the faster the particle gives up its soluble content. A very fine espresso grind has so much surface area that the water can extract 20 percent of the coffee's mass in 25 seconds under pressure. A coarse French Press grind has so little surface area that it takes four minutes of immersion to reach the same 20 percent. If you swapped grinds — used espresso-fine coffee in a French Press for four minutes — you would blow past 22 percent extraction and end up with a bitter, muddy cup. If you used French Press-coarse coffee in an espresso machine, you would extract perhaps 10 percent in 25 seconds and get a sour, watery shot. The grind size is what aligns the extraction rate with the brew time.

Within a single brew, the situation is more complex because your grinder produces a distribution of particle sizes, not a single size. The fines in your grounds extract almost instantly — within the first few seconds of a pour over or espresso shot, the fines have already given up most of their soluble content. The boulders extract slowly and may not fully extract even by the end of the brew. This is why a narrow particle distribution matters so much: if all your particles are close to the same size, they all extract at roughly the same rate, and your brew reaches the target extraction window as a coherent whole. If your distribution is wide — fines and boulders mixed together — the fines over-extract and the boulders under-extract, and the cup tastes of both problems at once. This is the bimodal distribution problem, and it is why a blade grinder produces a cup that tastes simultaneously harsh and weak.

There is also the matter of channeling, which is especially critical in percolation methods like pour over and espresso. Channeling happens when water finds a path of least resistance through the coffee bed and flows through that path rather than evenly through all the coffee. When water channels, it over-extracts the coffee along the channel and under-extracts the coffee elsewhere in the bed, so the cup tastes of both problems simultaneously. Finer grinds are more prone to channeling because they pack more tightly and create more resistance, which gives water more incentive to find a shortcut. This is why espresso requires careful puck preparation — WDT (Weiss Distribution Technique) stirring, leveling tamps, and paper filters on top of the puck — to distribute the water evenly through a very fine grind. It is also why pour over recipes include gentle agitation and a bloom phase: to keep the bed uniform and prevent the water from channeling through the fines that settle to the bottom.

You can learn to taste the difference between over- and under-extraction, and once you can, adjusting your grind becomes a matter of diagnosis rather than guesswork. Under-extracted coffee tastes sour — not bright and pleasant, but sharply acidic, almost vinegar-like, with a thin body that disappears quickly. The sourness lingers at the sides of your tongue. Over-extracted coffee tastes bitter — not the pleasant roast bitterness of a dark coffee, but a dry, astringent bitterness that coats your tongue and makes your mouth feel puckered. The bitterness builds as the cup cools. A balanced extraction has both acidity and bitterness but neither dominates: the cup has sweetness, body, and a clean finish. If you taste sourness, grind finer; if you taste bitterness, grind coarser. It sounds too simple to work, but once you calibrate your palate, it does.

Adjusting Your Grind — Troubleshooting

Dialing in a coffee is the process of finding the grind setting that produces a balanced extraction for your specific beans, brewer, and recipe. It is not a one-time task — you will need to adjust when you open a new bag, when the coffee ages, when the humidity changes, and sometimes from one day to the next for no obvious reason at all. The good news is that the adjustments are small and the feedback is immediate: brew a cup, taste it, change one variable, brew again, taste the difference. The goal is to build a mental model of how your grinder's settings map to the flavors in your cup, so that when something is off, you know which way to turn the dial.

The single most useful troubleshooting rule is this: if the coffee is bitter, go coarser; if it is sour, go finer. This rule covers the vast majority of grind-related problems, and it works because bitterness and sourness are the direct sensory signatures of over- and under-extraction. Bitterness means the water spent too long in contact with too much surface area — the late-stage compounds that should have stayed in the grounds are in your cup. Coarsening the grind reduces surface area and slows extraction, pulling those compounds back out of the cup. Sourness means the opposite: the water did not extract enough, and the acids that come out first are dominating the cup without the balancing sugars and bitters. Fining the grind increases surface area and speeds extraction, bringing those balancing compounds into the cup.

Make small adjustments. On a stepped grinder like the Baratza Encore, one click is roughly a 10 to 15 percent change in particle size, which is a noticeable but not drastic change in the cup. Move one click at a time, brew, taste, and repeat. On a stepless espresso grinder, a quarter-turn of the adjustment collar is often enough to change a shot from 25 seconds to 30 seconds, which is a meaningful difference in extraction. The temptation is to make large adjustments to "get there faster," but large adjustments overshoot the target and you end up oscillating between too fine and too coarse without ever landing in the middle. Small steps, taste, repeat.

For espresso specifically, channeling is the most common failure mode and it is not always fixed by changing the grind. If your shot is channeling — you will see it as a thin, fast-streaming jet from one side of the portafilter, or the shot will taste bitter and thin simultaneously — the problem may be puck preparation rather than grind size. Before you change the grind, check your distribution: use a WDT tool to stir the grounds in the portafilter basket and break up any clumps, then tamp level. A level tamp is critical: an uneven tamp creates a puck of varying density, and the water will flow through the least-dense section, which is channeling by definition. Only after you have ruled out distribution and tamping problems should you adjust the grind. If the puck is well-prepared and the shot is still channeling, go finer — a finer grind packs more tightly and resists channeling better, up to the point where the grind is so fine the shot stalls.

Keep a brew journal. It sounds tedious, but a simple notebook or a notes app entry for each dialing-in session — date, coffee, grind setting, dose, water temperature, brew time, and a one-line tasting note — turns dialing in from a guessing game into a data-driven process. After a few weeks you will notice patterns: this coffee from this roaster tastes best at setting 14 on your Encore, this other roaster's coffee needs setting 18. When the weather turns humid and your shots start running fast, you will have a record of what changed and you can adjust deliberately rather than blindly. A journal also helps you reproduce a great cup — if you nail a pour over that tastes perfect, write down the grind setting, because you will not remember it next week.

Finally, be patient with new coffee. A coffee that was roasted three days ago will extract differently than the same coffee after ten days of rest, because the degassing process (the release of CO₂ trapped during roasting) changes how the coffee bed behaves and how the water interacts with the particles. Fresh coffee off-gasses aggressively, which can cause channeling in pour overs and crema instability in espresso. Most specialty roasters recommend resting coffee 7 to 14 days after roast before brewing. If your first dialing-in session on a new bag is frustrating, brew it for three days in a row and let the coffee settle before you declare the grind wrong. The coffee changes; your grind should follow it.

Storing Coffee and Preserving Freshness

The grind you dial in with such care is only as good as the coffee you are grinding, and coffee is a perishable product with a steep flavor decline. Once roasted, coffee begins losing its volatile aromatics and changing its chemical composition within days. The compounds that make a fresh coffee taste vibrant and complex — the floral esters, the fruity acids, the caramelized sugars — are the first to go. What remains after a few weeks is a flatter, duller cup that tastes of roasted grain and cardboard, and no amount of grinding precision can bring back flavors that have already dissipated. Understanding how coffee ages and how to slow that aging is the final piece of the dialing-in puzzle, because stale coffee extracts differently from fresh coffee and will throw off your grind adjustments.

The first decision is whole bean versus pre-ground, and this is not close. Always buy whole bean and grind right before brewing. The reason is surface area again: a whole bean has minimal surface area exposed to oxygen, so it stales slowly. The moment you grind it, you shatter the bean and expose a massive amount of new surface area to the air — the same surface area that makes extraction fast also makes oxidation fast. Pre-ground coffee stales dramatically within hours of grinding; within a day it has lost most of its aroma and much of its flavor. This is why the coffee aisle in a supermarket, full of pre-ground coffee in bags that may have been sitting for months, is a wasteland compared to fresh whole beans from a local roaster. If you are buying a burr grinder on the strength of this guide, the corollary is that you should also stop buying pre-ground coffee immediately. The two decisions are inseparable.

Oxidation is the primary enemy, but it is not the only one. Light, heat, and moisture all accelerate the staling process. The ideal storage environment for coffee is a cool, dark, dry place in an airtight container. The bag your coffee comes in, if it has a one-way degassing valve and a resealable zip, is adequate for short-term storage — the valve lets CO₂ out without letting oxygen in, which is what you want for the first week or two after roast. For longer storage, or for coffee that comes in a non-resealable bag, transfer it to a dedicated coffee canister with an airtight seal. The Airscape (around $30) is a popular option that has a plunger lid to push out air; the Fellow Atmos (around $50) has a vacuum-sealing mechanism. Neither is necessary, but both extend the life of your coffee noticeably compared to a loosely folded bag.

Do not store coffee in the refrigerator. The temperature fluctuates every time you open the door, which causes condensation inside the container, and the coffee will absorb odors from whatever else is in the fridge — onions, garlic, leftovers, all of it. Refrigerator storage is a common piece of bad advice that ruins good coffee. The freezer, however, is a different story. Freezing coffee works, but it has to be done correctly: divide the coffee into small airtight portions (single-dose vials or small vacuum-sealed bags) so that you only open one portion at a time and the rest stays frozen. Do not freeze and thaw repeatedly; each thaw cycle introduces condensation and accelerates staling. A well-frozen single-dose portion, allowed to come to room temperature before opening (to prevent condensation on the cold beans), can preserve coffee for months with minimal flavor loss. Many competitive baristas brew competition coffee from frozen single-dose vials, so the technique is proven, not just theoretical.

How does stale coffee affect your extraction and your grind adjustments? Stale coffee has lost much of its soluble content — the volatile aromatics have evaporated, and some of the sugars have degraded. This means that a given grind setting will extract less from stale coffee than from fresh coffee, so you may find yourself grinding finer and finer to compensate, chasing a flavor that is no longer in the beans. The cup will taste hollow and flat regardless of your grind. This is the most insidious part of stale coffee: it makes you think your grind is wrong, when in fact the coffee itself is the problem. If you have been dialing in for a week and the cup is consistently mediocre no matter what you do, check the roast date on the bag. If it is more than four weeks past roast, the coffee is likely past its best and no grind setting will save it.

Aim to buy coffee in quantities you will consume within two weeks of opening. A 12-ounce bag, brewed at 18 grams per cup, is roughly 18 servings — about right for a daily drinker to finish in two to three weeks. Buy from a roaster who prints the roast date on the bag (not a "best by" date, which is often a year out and meaningless), and buy coffee roasted within the last two weeks. Grind fresh, brew immediately, store the rest well, and your carefully dialed-in grind will produce the cup you intended, cup after cup, until the bag is empty and it is time to start the process over again with a new coffee.