Coffee-to-water ratio calculator

What it calculates

This calculator finds the dry coffee dose for the water weight and ratio in your recipe. Enter both in grams, using the second number of the ratio: for 1:16, enter 16. The result tells you how much ground coffee to weigh before brewing the whole batch.

It helps when you want to resize a recipe you already use. Doubling the water while keeping the ratio doubles the coffee. Halving the water halves the dose. The recipe examples are arithmetic starting points, without a required ratio assigned to a particular brewer or brand.

Our gifts for coffee lovers guide explains how to choose around the equipment someone owns. The coffee gift shortlist includes scales, which make these measurements easier to repeat. A calculator can explain the quantities; the recipient still chooses a recipe that suits their equipment and taste.

How the ratio works

Divide the water weight by the ratio number. With 240 grams of water at 1:16, the calculation is 240 divided by 16. That gives 15 grams of dry coffee. Both quantities are masses, so the calculation needs no conversion between milliliters and grams.

Weigh the water that you will add to the coffee. Exclude water used only to rinse a paper filter or warm a cup. The amount you enter is also different from the drink you collect: some water remains in the grounds and filter after brewing.

As a documented reference, SCA 310-2021 defines a test ratio of 55 grams of coffee per 1,000 grams of water. We checked the scope and definitions of that edition on September 14, 2026. It covers electrical home filter brewers and excludes manual pour-over devices, French presses and espresso machines. Its test ratio cannot establish one recipe for all those methods.

The calculator accepts your chosen ratio instead. The initial 1:16 and the quick examples are illustrative recipes, without SCA endorsement. Results appear to one decimal place, while the underlying division keeps its precision. Record the actual dose your scale can measure if you want to repeat the batch later.

If your recipe lists only two weights, divide its water weight by its coffee weight to find the ratio number to enter. For example, 450 grams of water with 30 grams of coffee gives 15. Enter 15 to resize that same proportion for another batch.

Worked examples

For 240 grams of water at 1:16, weigh 15 grams of coffee. This is the dose for all the water entered, regardless of how many cups you will pour. If you want twice the batch, 480 grams at the same ratio requires 30 grams of coffee.

For 355 grams of water at 1:17, the exact result is about 20.882 grams. The displayed dose is 20.9 grams. This example uses weighed water; it does not treat a twelve-ounce cup as an exact water mass or promise that the finished drink will fill it.

For 1,000 grams of water at 1:12, the result is about 83.333 grams of coffee, displayed as 83.3 grams. Check the brewer's capacity before preparing that batch. Room for the water alone does not establish room for the grounds and the brewing process.

Limits of the result

The ratio does not measure extraction, dissolved solids or caffeine. Grind, beans, water composition, temperature and contact time are outside this calculation. A fixed caffeine multiplier based only on dry grounds cannot describe a particular finished drink, so the tool provides no caffeine estimate.

Follow your recipe's meaning of water and coffee. An espresso recipe comparing dry grounds with the weight of the finished drink uses a different relationship. Water added later to dilute a concentrate also needs a separate calculation. Keep the manufacturer's filling and operating instructions when scaling any recipe.