acalculator

How much coffee for my water?

Type how much water you will brew with, or how much ground coffee you have, and your ratio. The coffee calculator gives the other amount in grams, ounces, milliliters and cups.

Your numbers

Units
Start from
Brew
31.25 g coffee to 500 g water

Use 31.25 g coffee to 500 g water.

Coffee (g)
31.3
Coffee (oz)
1.1
Water (mL or g)
500
Water (fl oz)
16.9
Water (8 fl oz cups)
2.11
Coffee per liter (g/L)
62.5

Brew: 31.25 g coffee to 500 g water. Use 31.25 g coffee to 500 g water.

How to calculate

Works out how much ground coffee to use for an amount of water, or how much water for your coffee, at a brew ratio such as 1:16, in grams, ounces, milliliters and cups.

Example with the default inputs (Start from Water, Water 16.9070113509215 fl oz, Ratio 1 : 16): Use 31.25 g coffee to 500 g water.

Method: For a 1:N ratio, coffee grams = water grams ÷ N and water grams = coffee grams × N, with 1 mL of water = 1 g. Strength = 1,000 ÷ N grams per liter.

  • The ratio is by weight, brewing water to dry ground coffee. Water is taken as 1 g per mL.
  • The brewed coffee is less than the water you pour, because the grounds hold some back (about twice their weight).

Machine-readable copies: Markdown, JSON.

Worked examples

Each example is checked against the calculator on every build.

  1. Start from Water, Water 33.81 fl oz, Ratio 1 : 18 gives Coffee (g) 55.555556, Coffee per liter (g/L) 55.555556, Brew 55.56 g coffee to 1000 g water.Source: Wikipedia, Coffee preparation (brew ratios of water to coffee often 15–18:1 by mass; SCA 55 g of coffee per liter of water), https://en.wikipedia.org/wiki/Coffee_preparation (retrieved 2026-10-03)
  2. Start from Water, Water 16.91 fl oz, Ratio 1 : 16 gives Coffee (g) 31.25, Brew 31.25 g coffee to 500 g water.Source: Wikipedia, Coffee preparation (brew ratios of water to coffee often 15–18:1 by mass; SCA 55 g of coffee per liter of water), https://en.wikipedia.org/wiki/Coffee_preparation (retrieved 2026-10-03)
  3. Start from Coffee, Ground coffee 20 g, Ratio 1 : 15 gives Water (mL or g) 300, Water (fl oz) 10.144207, Water (8 fl oz cups) 1.268026.Source: Wikipedia, Coffee preparation (brew ratios of water to coffee often 15–18:1 by mass; SCA 55 g of coffee per liter of water), https://en.wikipedia.org/wiki/Coffee_preparation (retrieved 2026-10-03)

How it works

A ratio of 1:N means N grams of water for every gram of ground coffee, with 1 mL of water taken as 1 g.

  • From water: coffee grams = water grams ÷ N.
  • From coffee: water grams = coffee grams × N.
  • Strength: 1,000 ÷ N grams of coffee per liter of water.

The ratio N can be from 1 to 100 (16 by default). Units: 1 L = 1,000 mL; 1 US fl oz = 3,785.411784 ÷ 128 = 29.5735295625 mL; 1 cup = 8 fl oz; 1 oz = 28.349523125 g. Water can be up to 100 L; coffee up to 10 kg.

Exact arithmetic. Each value is read as the exact decimal you typed, in its unit, so each result is an exact fraction until it is rounded for display.

Output format. The answer line shows … g coffee to … g water, each to 4 significant figures with no thousands separators. The rows show grams, milliliters, fluid ounces and g/L to 1 decimal place, and ounces of coffee and cups of water to 2.

Assumptions

  • The ratio is by weight of brewing water to dry ground coffee.
  • Water weighs 1 g per mL; the small change with temperature is ignored.

Worked examples by hand

1 L at 1:18. Coffee = 1,000 ÷ 18 = 55.56 g, close to the SCA’s 55 g per liter.

The default, 500 mL at 1:16. Coffee = 500 ÷ 16 = 31.25 g.

20 g of coffee at 1:15. Water = 20 × 15 = 300 g = 300 mL = 300 ÷ 29.5735295625 = 10.14 fl oz = 1.27 cups.

Other questions people ask

What is a good coffee to water ratio?

Most brewing guides fall between 1:15 and 1:18 by weight: 15 to 18 g of water for each gram of coffee. 1:16 is a common middle. The Specialty Coffee Association’s standard of 55 g per liter is about 1:18.

How much coffee for 500 mL of water?

At 1:16, 500 ÷ 16 = 31.25 g of ground coffee. At 1:15 it is 33.3 g; at 1:18 it is 27.8 g.

How much water for 20 g of coffee?

Multiply by the ratio: at 1:15, 20 × 15 = 300 g of water, which is 300 mL or about 10.1 fl oz.

Why weigh water in grams?

One milliliter of water weighs about one gram, so grams and milliliters are the same number. A kitchen scale makes the ratio exact and repeatable.

Does the ratio change for French press or espresso?

French press and drip usually sit between 1:15 and 1:17. Espresso is much stronger, around 1:2 by the weight of the drink, so use a ratio of about 2 for it.

Why do I get less coffee than the water I poured?

The wet grounds keep some water, roughly twice their own weight. 30 g of coffee holds back about 60 g, so 500 g of water gives about 440 g of brewed coffee.