If you only change one thing about how you make coffee at home, grind size is a good place to start. It decides how fast water gets through the coffee and how much flavor it pulls out on the way. The same beans can taste sour, sweet, or bitter depending on nothing more than where the grinder is set.
Here is how grind size works, roughly where to start for each brewer, and how to adjust when a cup is not quite right.
Why grind size matters
Grinding breaks the bean into pieces, and water pulls flavor from the surface of those pieces. Finer grounds have more surface area and slow the water down, so they extract more. Coarser grounds have less surface area and let water through faster, so they extract less.
Too little extraction tastes sour, thin, and a little salty. Too much tastes bitter, dry, and hollow. The goal is the middle, where the coffee tastes sweet and balanced. Grind size is the easiest way to move toward it, because it changes extraction without changing your recipe.
A starting grind for each brewer
Every grinder is labeled differently, so these are descriptions rather than numbers. Use them as a first setting, then adjust by taste.
- Espresso: fine, a bit finer than table salt. It should clump slightly when pinched.
- Moka pot: fine to medium-fine, a little coarser than espresso.
- AeroPress: medium-fine for short brews, closer to medium for longer steeps.
- Pour-over (V60, Kalita, and similar): medium-fine, roughly like coarse sand.
- Flat-bottom drip machine: medium, like regular sand.
- Chemex: medium-coarse. The thick filter slows the flow, so it needs a little more room.
- French press: coarse, like sea salt.
- Cold brew: coarse to extra coarse, like rough sea salt or cracked pepper.
How to tell which way to adjust
- Sour, sharp, or thin, and the brew ran fast: grind finer.
- Bitter, dry, or harsh, and the brew ran slow or stalled: grind coarser.
- Muddy or flat, with lots of fine sediment: the grinder may be producing uneven particles. A cleaner burr grinder helps more than any setting change.
Make one small change at a time and keep everything else the same, including dose, water, and timing. That way you know what actually made the difference.
Burr grinders versus blade grinders
A blade grinder chops coffee at random, so you end up with a mix of dust and chunks. The dust over-extracts and the chunks under-extract, and the cup ends up bitter and sour at once. A burr grinder crushes beans between two surfaces set a fixed distance apart, which gives much more even pieces. Even an inexpensive hand burr grinder is a real step up.
Roast and freshness change things too
Lighter roasts are denser and harder to extract, so they often taste better a touch finer. Darker roasts extract easily and usually like a slightly coarser setting. Very fresh coffee that is still giving off carbon dioxide can also brew unevenly, which is one more reason to let beans rest a few days after the roast date.
We roast in small batches and ship whole bean, so you can grind each cup right before you brew it. Ground coffee loses aroma within minutes, and grinding fresh is one of the simplest ways to get more out of a good bag.
The short version
Start with the grind that fits your brewer, taste, and adjust in small steps. Sour usually means go finer, bitter usually means go coarser, and an even burr grinder makes every setting work better.