Coarse — roughly the consistency of coarse sea salt or rock candy. A French press uses immersion brewing (the coffee sits in the water), so a fine grind would over-extract very quickly and leave the cup full of sludge.

What grind size do I need for French press?

Coarse — roughly the consistency of coarse sea salt or rock candy. A French press uses immersion brewing (the coffee sits in the water), so a fine grind would over-extract very quickly and leave the cup full of sludge.

Why this is the case

A French press operates on a fundamentally different principle than a pour-over cone or an espresso machine. With a French press, the coffee grounds remain fully submerged in the water for the entire duration of the brew (typically 4 minutes) — a process known as immersion brewing. There is no paper filter separating the water from the coffee while it steeps. This means the contact time is very long, and the grind size must be adjusted accordingly.

Fine coffee grounds would hopelessly over-extract during a 4-minute steep — the result would be bitter, harsh, and unpleasant. Additionally, the metal mesh screen of a French press lets fine particles pass right through. The finer you grind, the more sediment ends up in your cup. The result is a muddy, gritty coffee with sludge at the bottom and a powdery mouthfeel.

A coarse grind solves both problems. The large particles extract much more slowly, allowing a balanced cup to develop even over a 4-minute steep. Furthermore, they are large enough to be reliably held back by the metal plunger screen.

As a reference: The particles should be about the size of coarse sea salt or lightly crushed peppercorns. You should be able to clearly see the individual chunks with the naked eye. If the grounds look like fine sand, they are too fine for a French press.

A steep time of 4 minutes is the standard starting point. If you prefer a milder coffee, you can shorten it to 3:30. If you want more body and intensity, you can extend it to 5–6 minutes — but you must grind even coarser to avoid bitterness.

A quick tip to prevent sediment: Once you plunge the filter down, immediately pour the coffee into another carafe or your cups. If you leave the brewed coffee sitting in the French press, it will continue to extract because the grounds at the bottom remain in contact with the hot water.

In practice at Green Wall Coffee

At our café on Sophienstraße 27, we offer French press as an alternative to pour-over filter coffee. We grind it significantly coarser than we do for our V60s — the difference is obvious just by looking at it. Whenever guests complain that their French press coffee at home is muddy or bitter, the solution is almost always the same: grind coarser. It is the single most common mistake made with this brewing method.

Related questions

• What grind size do I need for filter coffee?
• How to brew French press coffee correctly?
• Why does my French press coffee taste muddy?

For more depth on the subject, check out our V60 pour-over guide. Or visit us at Sophienstraße 27 — Mon–Fri 8am–5pm, Sat 10am–5pm.