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Coffee to Water Ratio

Find the coffee, water or ratio that fits your brew. Choose what to solve for, enter the other values, then press Convert.

Written and reviewed by SM Arijul Islam · Last reviewed 29 October 2026 · Editorial standards · Report an error

About the Coffee to Water Ratio

Coffee brewing ratios are written as 1:15, 1:16 or 1:17 — one part coffee to that many parts water by weight. A 1:16 ratio with 18 g of coffee needs 288 g of water. Using weight rather than volume avoids the huge variation in how much a scoop of coffee holds.

Strength is a preference, but the ratio also interacts with grind and contact time. A 1:15 brew is concentrated and works for immersion; 1:17 is lighter and common for filter. If the cup tastes weak, tighten the ratio or grind finer before adding more coffee; if it is bitter, coarsen the grind or shorten the brew.

How the calculation works

Water (g) = coffee (g) × ratio.
Coffee (g) = water (g) ÷ ratio.
Ratio = water (g) ÷ coffee (g).
1 cup = 240 mL; brewed coffee is close to 1 g/mL.

Reference values

Common brew ratios
Ratio	Coffee for 300 g water	Character
1:12	25.0 g	Very strong, immersion
1:15	20.0 g	Strong filter
1:16	18.8 g	Standard filter
1:17	17.6 g	Light filter
1:18	16.7 g	Very light

Worked example: 20 g of coffee at 1:15

For a 1:15 ratio and 20 g of coffee, use 300 g of water. If you want 250 g in the cup and the grounds retain about 2 g of water per gram of coffee, start with 250 + 40 = 290 g of water, which is a 1:14.5 ratio. For a 1:17 ratio, 18 g of coffee needs 306 g of water.

Use grams on a scale rather than a scoop. Water is close to 1 g/mL, but coffee is not, and a scoop varies with grind, roast and how it is filled. Weight makes the ratio repeatable, which is the first step towards changing one variable at a time.

Frequently asked questions

Should I use grams or scoops?

Grams. A tablespoon of coffee can range from about 5 g to 9 g depending on grind and roast, which is enough to change the ratio by nearly 50%.

Does the ratio include water retained by the grounds?

No. The ratio is water poured versus dry coffee. The brewed yield is lower because the grounds retain roughly twice their weight in water.

What ratio for cold brew?

Cold brew often uses 1:8 for concentrate, then dilutes 1:1 or 1:2 with water or milk. Use the ratio field to scale the concentrate.

Should I use grams or millilitres?

Use grams on a scale. Water is close to 1 g/mL, but coffee is not, and a scoop varies with grind and roast. Weight makes the ratio repeatable.

Sources and standards

Brew ratios are expressed as grams of coffee to grams of water, with water treated as 1 g/mL at room temperature. The Specialty Coffee Association publishes the brewing control chart behind the ratios in common use, and the page states when a figure is a starting point rather than a rule.