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Coffee to Water Ratio Calculator

Enter the values to get the coffee needed.

How it is calculated

The ratio is read as grams of water per 1 gram of coffee, as in 1 : 16. The formula is coffee (g) = water (g) ÷ ratio. Water is in grams, which for brewing is the same as millilitres. The ratio is the second number only, so type 16 for 1 : 16, not 1:16 or 0.0625. The result is rounded to two decimals. Water of 0 is accepted and gives 0 g of coffee. A ratio of 0 or below, or a negative water amount, gives no result.

Worked example

You want 350 g of water at a ratio of 1 : 15.5. Divide the water by the ratio: 350 ÷ 15.5 = 22.58. So you need 22.58 g of coffee. A scale reading 22.6 g is close enough. The tool echoes the ratio back as 1 : 15.5, so you can confirm it read your value correctly.

Try this example →

Common mistakes

  • Entering the ratio as a coffee share, for example 0.06 or 6 for 6 percent. The tool expects the water number from 1 : N, such as 16.
  • Putting the coffee amount in the water box. The water field is the amount of water you will pour, and the coffee comes out as the result.
  • Swapping the ratio direction. A 1 : 16 ratio means less coffee than 1 : 12, so a bigger number gives a weaker cup.
  • Measuring water in cups or ounces but reading the result in grams. Convert the water to grams or millilitres first.

About this calculator

Coffee brewing strength is controlled by the ratio of coffee grounds to water by weight, commonly written as 1:15 to 1:18 for drip coffee or roughly 1:2 for espresso. Given a target water amount and a chosen ratio, the needed coffee is simply water ÷ ratio — for example, 500g of water at a 1:16 ratio calls for 500 ÷ 16 ≈ 31g of coffee.

Home baristas and coffee professionals rely on this ratio-based approach — rather than fixed scoop measurements — because it scales precisely to any batch size and produces a consistent, repeatable brew strength across different pot or cup sizes. Specialty coffee guides and roasters typically recommend a specific ratio range depending on the brew method, and this calculator lets someone dial in the exact gram amount for their equipment.

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