A filter machine wants a medium grind, roughly the texture of coarse sand or table salt.
Where it sits
Coarser than espresso and moka, finer than French press, similar to a Kalita Wave, slightly coarser than a V60.
Adjusting by drain time
The basket tells you. For a full batch:
Drains in under 4 minutes — too coarse. The coffee will be weak and sour. Grind finer.
Still dripping after 7 minutes — too fine. Fines are clogging the paper, and the brew will be bitter. Grind coarser.
4 to 6 minutes is the target.
The flat-bottom factor
Most machine baskets are flat-bottomed, which gives a more even bed and a more forgiving extraction than a cone. That is why machine grind is a little more tolerant than V60 grind.
The bed depth problem
A shallow bed channels regardless of grind. If you regularly brew two cups in a ten-cup basket, the fix is a smaller machine, not a finer grind.
Pre-ground for machines
Supermarket “filter grind” is aimed here and is usually about right. It is also stale, which matters more than the grind being perfect.
The commonest actual problem
Not grind at all — ratio. Machine markings assume far less coffee than 60 g per litre. Weigh the coffee and most complaints about weak machine coffee disappear.
Last reviewed 8 August 2026