What grind size should I use for pour over?

Commonly medium, in the region of 400 to 800 microns, roughly like table salt to coarse sand. A practical check is timing: after the bloom, the bed should drain in about two to three minutes. If it drains much faster, grind finer; if it stalls, grind coarser.

Why does my coffee taste sour?

Sour, sharp and thin is the classic signature of under-extraction, which usually means the grind is too coarse, the water too cool, the ratio too weak or the brew too short. Grinding finer is the first thing to try, changing only that one variable.

Why does my coffee taste bitter?

Bitter, dry and harsh usually indicates over-extraction: too fine a grind, too hot a water, too strong a ratio or too long a brew. Grinding coarser is the usual first adjustment, though very uneven grinding can produce bitter and sour notes in the same cup.

Do I need a different grind for each brew method?

Yes. Espresso needs a very fine grind to create resistance, immersion brewers need a coarse one, and filter methods sit in between. Within a method, the exact setting also shifts with the specific coffee, its roast level and its age.

Can I reuse ground coffee left in the grinder?

It is better not to rely on it. Grounds left in the chute or hopper oxidise quickly and lose aroma, so they will flatten the next cup. If a grinder retains a lot, single-dosing measured amounts before grinding avoids the problem entirely.

/glossary/grind-size

Grind Size

研磨度

Grinding

By The Cupping Room · Published 2 September 2026

Definition

The average particle diameter of ground coffee, set by the gap between the grinder's burrs or by how long a blade grinder runs. It is the single most powerful variable a brewer controls: finer grounds expose more surface area and slow the flow of water, speeding extraction, while coarser grounds do the opposite. Every brew method has a working range - espresso near 200 microns, filter coffee roughly 400 to 800, French press beyond 1000.

Etymology

Grind comes from the Old English grindan, to rub together or crush; size became a standard label in coffee retail only in the mid-20th century, as roasters began printing brew-specific directions on bags.

In use

The first dial a barista touches when a shot runs too fast or too slow - 'the grind was too coarse' explains a gushing espresso in three words.

Why Particle Size Governs Extraction

Water can only dissolve what it touches. A coffee particle gives up its soluble material through its surface, so a fine particle, which has far more surface area for its weight, releases its contents much faster than a coarse one. Grinding finer therefore speeds extraction; grinding coarser slows it. Almost every other brewing variable works by changing this relationship indirectly.

There is a second effect that is easy to miss. Fine particles also pack together more tightly, which increases resistance to water flow. In a percolation brew such as pour over or espresso, a finer grind both speeds up extraction per particle and slows down the flow of water through the bed. Those two effects pull in the same direction for flavour but opposite directions for time, which is why a fine grind can produce a very short brew that still tastes over-extracted.

In an immersion brew such as a French press, there is no flow to slow because the water is already in contact with everything. That is why grind size in immersion brewing mostly affects extraction rate and how much sediment reaches the cup, and much less the timing of the brew.

Reference Ranges for Common Brewers

The numbers below are working ranges rather than standards, and every grinder's scale is its own. Espresso sits at the finest end, commonly in the region of 200 microns, with Turkish coffee finer still. Moka pots typically want something a little coarser than espresso. Pour over, drip and Aeropress cluster in the middle, roughly 400 to 800 microns depending on the recipe and the filter.

French press and other full-immersion brewers sit at the coarse end, generally beyond 1000 microns so that the mesh does not clog and the plunge stays easy. Cold brew often uses the coarsest setting of all, because the long steep of twelve hours or more compensates for the slow extraction of large particles.

A more useful way to think about it is in terms of texture. Fine is finer than table salt and closer to flour; medium is like table salt or slightly coarser; medium-coarse resembles coarse sand or sea salt; coarse is closer to peppercorns or breadcrumbs. If you can identify the texture, you can get close to the right setting on an unfamiliar grinder before you brew anything.

Adjusting by Taste Rather Than by Chart

Charts get you into the right region; taste gets you to the right point. Under-extracted coffee tastes sour, sharp, thin and sometimes salty, with a short finish. Over-extracted coffee tastes bitter, dry, harsh and hollow, with an astringent aftertaste. If you taste the first group, grind finer; if you taste the second, grind coarser. Make one adjustment, then brew again.

Change the grind in small steps. On an espresso grinder, that may mean the smallest adjustment the machine allows; on a hand grinder, one or two clicks. Large jumps make it impossible to know whether you passed the good setting or were never near it. If a big change is needed, change it in two stages and taste between them.

Remember that grind is not the only lever. Water temperature, ratio and brew time all shift extraction too, and changing several at once makes the result unattributable. A workable discipline is to fix the ratio and temperature, then use grind as the single adjustment until the coffee tastes right, and only afterwards consider fine-tuning the others.

Fines, Distribution and Grinder Limits

Every grinder produces a spread of particle sizes rather than one exact size, and the smallest of those particles are called fines. Fines extract very quickly and can taste harsh, and they also migrate downward through a coffee bed during percolation, packing against the filter and slowing the flow late in the brew. A brew that starts fast and then stalls is usually a fines problem rather than a grind-setting problem.

Fines cannot be eliminated, only reduced. Better burrs, a slower feed rate, and grinding coarser all help. Some brewers sift the fines out with a dedicated sieve, which produces a very clean cup at the cost of wasted coffee and extra work. For most people, accepting a modest amount of fines is more sensible than chasing a perfect distribution.

Grinder quality sets a ceiling here. A grinder with a wide distribution will always produce a mixture of under- and over-extracted flavours, no matter how carefully the setting is chosen. This is why grind size advice is only as good as the grinder producing it, and why upgrading the grinder changes the cup more than upgrading the brewer.

Practical Habits and Common Mistakes

Grind immediately before brewing. Ground coffee loses aroma quickly because of the enormous surface area exposed to air, and pre-ground coffee from a shop is usually stale within days. If you must grind ahead, keep it sealed and use it within a day or two, accepting a flatter cup.

Re-check the setting when you change beans. Density, roast level, bean size and age all change how a coffee behaves in the grinder and how fast it extracts. A setting that produced a perfect brew from one bag can be noticeably wrong for the next, and the same bag will drift over the two or three weeks it takes to finish.

Do not chase a grind setting printed on a bag. Those recommendations are written for an unknown grinder and an unknown brewer, and they are a starting hint at best. Equally, do not assume that a grinder's numbered settings mean anything transferable: the same number on two machines can be a full step apart in actual particle size.

Questions

What grind size should I use for pour over?: Commonly medium, in the region of 400 to 800 microns, roughly like table salt to coarse sand. A practical check is timing: after the bloom, the bed should drain in about two to three minutes. If it drains much faster, grind finer; if it stalls, grind coarser.
Why does my coffee taste sour?: Sour, sharp and thin is the classic signature of under-extraction, which usually means the grind is too coarse, the water too cool, the ratio too weak or the brew too short. Grinding finer is the first thing to try, changing only that one variable.
Why does my coffee taste bitter?: Bitter, dry and harsh usually indicates over-extraction: too fine a grind, too hot a water, too strong a ratio or too long a brew. Grinding coarser is the usual first adjustment, though very uneven grinding can produce bitter and sour notes in the same cup.
Do I need a different grind for each brew method?: Yes. Espresso needs a very fine grind to create resistance, immersion brewers need a coarse one, and filter methods sit in between. Within a method, the exact setting also shifts with the specific coffee, its roast level and its age.
Can I reuse ground coffee left in the grinder?: It is better not to rely on it. Grounds left in the chute or hopper oxidise quickly and lose aroma, so they will flatten the next cup. If a grinder retains a lot, single-dosing measured amounts before grinding avoids the problem entirely.