Spoke · French press ratio
French press ratio by press size
For a French press, weigh roughly 1 gram of coffee for every 15 to 18 grams of water. The table below turns that into grams for the common 8, 12, 17, 34 and 51 oz presses, shows where published recipes disagree, and the calculator handles any amount of water.
Grams of coffee by press size
Each row assumes you brew with the press’s rated capacity in water, converted at 1 fl oz = 29.57 ml and 1 ml of water ≈ 1 g. In practice you will pour a little less (see how full to fill), so weigh your actual water and use the calculator for exact numbers.
| Press (rated) | Water | 1:12 strong | 1:15 | ≈1:16.7 30 g / 500 ml | ≈1:18.2 SCA 55 g/L | Bodum scoops |
|---|---|---|---|---|---|---|
| 8 oz single mug | 237 g | 19.7 g | 15.8 g | 14.2 g | 13.0 g | 2 |
| 12 oz Bodum 3-cup, 0.35 l | 355 g | 29.6 g | 23.7 g | 21.3 g | 19.5 g | 3 |
| 17 oz Bodum 4-cup, 0.5 l | 503 g | 41.9 g | 33.5 g | 30.2 g | 27.6 g | 4 |
| 34 oz Bodum 8-cup, 1.0 l | 1005 g | 83.8 g | 67.0 g | 60.3 g | 55.3 g | 8 |
| 51 oz Bodum 12-cup, 1.5 l | 1508 g | 125.7 g | 100.5 g | 90.5 g | 82.9 g | 12 |
The 1:16.7 column is the Wikipedia French press article’s “about 30 g … to 500 ml” and the closest single starting point. The 1:12 column is the strong end of the published range, which ESPRO suggests for light roasts. Scoops follow BODUM’s one scoop per 4 oz cup; the 8 oz row is our arithmetic from that rule, since BODUM’s smallest Chambord in its instructions is the 12 oz 3-cup.
The formula
water (g) ≈ water (ml) (1 ml of water ≈ 1 g)
coffee (g) = water (g) ÷ ratio
SCA 55 g/L as a ratio: 1000 ÷ 55 ≈ 18.2
coffee in the cup (g) ≈ water − 3 × coffee (immersion grounds hold ≈3 ml per gram)
Worked example: a 17 oz press filled to 17 oz holds 17 × 29.57 ≈ 503 g of water; at 1:16.7 that is 503 ÷ 16.7 ≈ 30 g of coffee. The grounds keep some water back: Barista Hustle puts the liquid retained in immersion brewing at about 3 ml per gram of coffee, so roughly 503 − 3 × 30 ≈ 413 g reaches the cup.
Where the sources disagree
| Source | What it says | As a ratio |
|---|---|---|
| SCA brewing best practices | 55 g per liter ± 10% (general brewing reference, not French press only) | ≈1:18.2 (≈1:16.5–1:20.2) |
| Wikipedia, French press | about 30 g to 500 ml, “more or less to taste” | ≈1:16.7 |
| National Coffee Association | 1 g of coffee to 10–16 g of water | 1:10–1:16 |
| BODUM instructions | 1 rounded tablespoon or 1 BODUM scoop per 1.25 dl (4 oz) cup | ≈1:16.7–1:18.2* |
| ESPRO, 18 oz press | by roast: dark 1:18, medium 1:15, light 1:12 | 1:12–1:18 |
| Stumptown, 8-cup press | 56 g coffee, water to 850 g | ≈1:15.2 |
| Sightglass, 4-cup press | 38 g coffee, 600 g (20 oz) water | ≈1:15.8 |
* BODUM gives volume, not grams. Seattle Coffee Gear’s guide to the Bodum Brazil puts a full 8-cup (1.0 L / 34 oz) press at “roughly 55–60g” of ground coffee, which by our arithmetic is about 1:16.7 to 1:18.2. That guide words the rule as a rounded teaspoon per 4 oz, while BODUM’s own instructions say a rounded tablespoon; we follow the manufacturer.
So the roaster recipes cluster around 1:15 to 1:16, the SCA reference is lighter, and the NCA and ESPRO allow much stronger brews. All of them are starting points: pick 1:15 or 1:16.7, taste, and move in steps of about one ratio point. The general coffee-to-water ratio guide explains what strength and extraction mean.
- 8 oz — 237 g water, about 14 g coffee at 1:16.7.
- 12 oz (BODUM 3-cup, 0.35 l) — 355 g water, about 21 g coffee.
- 17 oz (BODUM 4-cup, 0.5 l) — 503 g water, about 30 g coffee.
- 34 oz (BODUM 8-cup, 1.0 l) — 1005 g water, about 60 g coffee.
- 51 oz (BODUM 12-cup, 1.5 l) — 1508 g water, about 90 g coffee.
How full to fill, and what a “cup” means
- A press “cup” is about 4 oz. BODUM defines a cup as 1.25 dl (4 oz), and Seattle Coffee Gear notes that an 8-cup press makes eight 4 oz servings, not eight US mugs. An 8 fl oz US cup is twice that; see how much coffee per cup for the other cup definitions.
- Labels are not standard across brands. BODUM sells 12, 17, 34 and 51 oz sizes; Frieling lists 17, 23, 36 and 44 oz. Sightglass brews 600 g of water in what it calls a 4-cup press, more than the 0.5 l that BODUM’s 4-cup holds. Weigh the water rather than trusting the cup count.
- Leave headroom. BODUM’s instructions say to leave at least 2.5 cm (1 inch) of space at the top; ESPRO says to fill to the maximum line inside the press. Stumptown fills its 8-cup press to 850 g, to the top of the metal collar.
French press calculator
Water = 34 fl oz × 29.57 ≈ 1005 g · coffee = 1005 ÷ 16.67 ≈ 60.3 g · ≈ 8.0 BODUM scoops (1 per 4 oz) · cup ≈ 1005 − 3 × 60.3 ≈ 824 g
Step by step, by weight
- Pick the water amount for your press, leaving about an inch of headroom, and read the coffee dose from the table or calculator.
- Heat the water to 93–96 °C (199–205 °F); the SCA’s target is 200 °F ± 5° at the point of contact. The water guide covers altitude.
- Weigh and grind the coffee coarse, about the texture of cooking salt (the NCA says rock salt). See the grind chart.
- Tare the press with the grounds on a scale, start a timer and pour the water to your target weight. Stumptown pours about half (450 g of 850 g) first and stirs at 1:00; the NCA waits about a minute for a crust to form, then stirs.
- Lid on, plunger up, steep about 4 minutes. BODUM says at least 4 minutes; the SCA’s general contact time for a coarse grind is 6–8 minutes, worth trying if the cup tastes thin.
- Plunge slowly and pour everything out so the coffee does not keep steeping on the grounds. Technique details and troubleshooting are in the French press guide.
Checklist
- Know your press’s real capacity in fl oz or ml (not just the “cup” count)
- Water weight chosen, with about 1 inch of headroom
- Ratio chosen: start at 1:15–1:16.7
- Coffee weighed: water ÷ ratio
- Coarse grind
- Water at 93–96 °C (199–205 °F)
- Timer at about 4 minutes, then a slow plunge
- Pour out all the coffee right away
Lab tip: write down the water weight your press actually takes to its fill line once. After that, the dose is a single division, and the printable ratio chart covers other brewers.
Sources
- Wikipedia — French press (secondary: about 30 g of coffee to 500 ml of water, 93–96 °C, about four minutes)
- Specialty Coffee Association — Protocols & Best Practices (55 g/L ± 10%; 200 °F ± 5°; 6–8 minutes contact for a coarse grind)
- National Coffee Association — About Coffee: French press coffee (1:10 to 1:16, 93 ± 3 °C, crust at about one minute, about four minutes)
- BODUM — Chambord coffee maker instructions (PDF hosted by Amazon: 1 rounded tbsp or 1 scoop per 1.25 dl / 4 oz cup; leave 2.5 cm / 1 inch at the top; at least 4 min; 3/4/8/12-cup capacities)
- Seattle Coffee Gear — Bodum Brazil French Press 8 Cup product guide (1 cup = about 4 oz; 1.0 L / 34 oz; full press roughly 55–60 g)
- Seattle Coffee Gear — Bodum replacement glass (sizes 3 cup 0.35 l 12 oz, 8 cup 1.0 l 34 oz, 12 cup 1.5 l 51 oz)
- Everything Kitchens — Frieling French press listing (17, 23, 36 and 44 oz sizes)
- ESPRO — 18 oz French press coffee brewing guide (1:18 dark, 1:15 medium, 1:12 light roast; fill to the max line; up to 4 minutes)
- Stumptown Coffee Roasters — French press brew guide (8-cup press: 56 g coffee, 450 g then to 850 g water, stir at 1:00, press at 4:00)
- Sightglass Coffee — French press brewing guide (4-cup press: 38 g coffee, 600 g / 20 oz water, four-minute timer)
- Barista Hustle — Liquid Retained Ratios (immersion brews hold back about 3 ml of water per gram of coffee)
- NIST Office of Weights and Measures — Approximate Conversions from U.S. Customary Measures to Metric (1 fl oz = 29.57 mL)