Coffee Ratio Calculator

Work out coffee and water for a 1:N brew ratio from coffee grams, water amount or cups, with tablespoons, fluid ounces and brewed yield after retention.

Interactive calculator · Method COFFEE-RATIO-1.0 · Last reviewed: 2026-11-04

Calculate your scenario

With a 1:N ratio measured as brew water in, water = coffee × N and coffee = water ÷ N.

Your inputs

Try an example

Start from

Coffee (when starting from coffee) (g)

Water (when starting from water) (g/ml or fl oz)

Water unit for the water entry

Number of cups (when starting from cups) (cups)

Brew water per cup (ml)

Ratio source

Custom ratio N (1 g coffee : N g) (N)

N measures

Ground coffee per tablespoon (example 5 g) (g/tbsp)

Water kept by wet grounds (example 2 g per g) (g per g coffee)

Default worked example. Edit the inputs to calculate your scenario.

Default worked example

Coffee 30 g

Brew water 480 g (ml) / 16.2 fl oz

Approx. tablespoons of coffee 6 tbsp

Brewed yield after retention 420 g (ml) / 14.2 fl oz

Ratio used 1:16 (water in)

Coffee 30 g × 16 = 480 g water; yield = 480 − 2 × 30 = 420 g.

How to use the calculator

Choose what you start from and fill that field, pick a preset ratio or enter your own N, say whether N counts water in or beverage out, then adjust the tablespoon weight and retention if you know them.

What the result means

At 1:16, 30 g of coffee takes 480 g of water and, with grounds holding about 2 g per gram, leaves roughly 420 g of brewed coffee.

Formula and units

With a 1:N ratio measured as brew water in, water = coffee × N and coffee = water ÷ N. Measured as beverage out, water = coffee × (N + retention) because the grounds keep retention × coffee grams of water. Brewed yield = water − retention × coffee. Water is taken as 1 g per ml; 1 US fl oz = 29.5735 ml; tablespoons = coffee ÷ grams per tablespoon.

Worked examples

30 g coffee at 1:16: Coffee (when starting from coffee): 30 g; Water (when starting from water): 500 g/ml or fl oz; Number of cups (when starting from cups): 2 cups; Brew water per cup: 250 ml; Custom ratio N (1 g coffee : N g): 16 N; Ground coffee per tablespoon (example 5 g): 5 g/tbsp; Water kept by wet grounds (example 2 g per g): 2 g per g coffee; Start from: coffee; Water unit for the water entry: g; Ratio source: custom; N measures: in.
Example result: Coffee: 30 g; Brew water: 480 g (ml) / 16.2 fl oz; Approx. tablespoons of coffee: 6 tbsp; Brewed yield after retention: 420 g (ml) / 14.2 fl oz; Ratio used: 1:16 (water in).

12 fl oz French press at 1:15: Coffee (when starting from coffee): 30 g; Water (when starting from water): 12 g/ml or fl oz; Number of cups (when starting from cups): 2 cups; Brew water per cup: 250 ml; Custom ratio N (1 g coffee : N g): 16 N; Ground coffee per tablespoon (example 5 g): 5 g/tbsp; Water kept by wet grounds (example 2 g per g): 2 g per g coffee; Start from: water; Water unit for the water entry: floz; Ratio source: press; N measures: in.
Example result: Coffee: 23.7 g; Brew water: 355 g (ml) / 12 fl oz; Approx. tablespoons of coffee: 4.7 tbsp; Brewed yield after retention: 308 g (ml) / 10.4 fl oz; Ratio used: 1:15 (water in).

Limitations and common mistakes

The preset ratios are common examples, not optimal recipes; taste, grind and brewer change what works. Grams per tablespoon depends on roast and grind, so weigh coffee when you can. Retention varies by brewer and grind. Cup size means brew water per cup, not mug capacity.

Using an espresso-style “1:2” (beverage out) as if it were brew water in understates the water by the amount the puck keeps.

Sources and assumptions

Method COFFEE-RATIO-1.0; last formula review 2026-11-04. Sources and their supported claims. Calculation methodology.