The short answer: 1:12
A French press coffee ratio of 1:12 means one part coffee to twelve parts water by weight. That is noticeably stronger than the 1:16 used for drip, and the reason is the brew method. In a French press the grounds sit in the water the whole time, but the coarse grind and the paperless metal filter extract less aggressively per minute than a pour over's steady flow of fresh water. The stronger ratio keeps the cup from tasting washed out.
Because 1 milliliter of water weighs 1 gram, you can work entirely in grams and milliliters. Weigh your water in milliliters, divide by 12, and that is your coffee dose in grams. A kitchen scale makes this exact; tablespoons get you close enough on a weekday morning.
Worked example 1: a full 32 oz press
A 32 oz French press holds about 946 milliliters of water. Divide 946 by 12 and you get 78.9 grams of coffee, which converts to about 10.5 tablespoons at 7.5 grams per tablespoon. In practice, call it 79 grams or 10 heaping tablespoons. Use a coarse grind, roughly the texture of sea salt, and water just off the boil, 195 to 205 F.
The method: add the grounds, pour in the water, stir once to wet everything, and set a timer for 4 minutes. At 4 minutes, break the crust, skim the foam, plunge slowly, and decant right away so the coffee stops steeping. Coffee left sitting on the grounds keeps extracting and turns bitter within minutes.
Worked example 2: a 1-liter press
Many presses are sold as 1 liter (34 oz). One liter of water is 1,000 grams, so 1,000 divided by 12 gives 83.3 grams of coffee, or about 11.1 tablespoons. The difference between the 32 oz and 1-liter dose is small, about half a tablespoon, which is why most people dose either press at roughly 11 tablespoons and adjust from there.
If 83 grams tastes too intense, do not reach for a finer grind first. Keep the grind coarse and loosen the ratio to 1:13, which gives 76.9 grams per liter. Change one variable at a time so you know what fixed the cup.
Worked example 3: a single 12 oz mug
For one big mug, 12 oz of water is about 355 milliliters. Divide 355 by 12 to get 29.6 grams of coffee, or about 3.9 tablespoons. Call it 30 grams or 4 level tablespoons. The same 4-minute steep applies. This is the dose to memorize if you brew one press cup a day: 4 tablespoons, 12 ounces, 4 minutes.
Scaling down further works the same way. An 8 oz cup (237 ml) needs 19.8 grams, about 2.6 tablespoons. A 20 oz travel mug (591 ml) needs 49.3 grams, about 6.6 tablespoons. The coffee ratio calculator runs these conversions for any press size in grams, tablespoons, or cups.
Grind size matters as much as the ratio
French press demands a coarse grind. Fine grounds slip through the metal mesh and make the cup silty, and they over-extract during the long steep, adding harshness. If your press coffee tastes bitter even at the right ratio, the grind is the first suspect. It should look like coarse sea salt, with distinct particles and no powder.
Blade grinders make this harder because they produce a mix of boulders and fines no matter how long you pulse. A burr grinder set coarse gives a uniform particle size, which is the single biggest upgrade most French press brewers can make, bigger than changing the ratio.
Dialing the ratio to your taste
Treat 1:12 as the starting point, not a law. If the cup tastes thin or sour, tighten toward 1:11, which is 85.9 grams per liter. Sourness in a press usually means under-extraction, and more coffee relative to water fixes it faster than a longer steep. If the cup tastes harsh or muddy, loosen toward 1:13 or 1:14 rather than grinding finer, which risks more silt.
Keep a simple log for a week: dose in grams, grind setting, steep time, and a one-word verdict. The ratio that tastes best becomes your personal house ratio. Most press drinkers land between 1:11 and 1:14, and that whole range is normal.