Coffee to Water Ratio Calculator

Good coffee starts before the kettle boils. The coffee to water ratio sets the strength target, while grind size and brew time decide whether that strength tastes sweet, harsh, hollow, or balanced. This calculator turns a known amount of coffee or water into the matching brew amount for pour over, drip, French press, and cold brew.

How the brewing math works

The calculator starts with three choices: brewing method, regular or strong strength, and whether the amount you entered is coffee or water. Each method has two ratios. Pour over or drip uses 1:17 for regular and 1:15 for strong. French press uses 1:17 for regular and 1:11 for strong. Cold brew uses 1:8 for regular and 1:5 for strong.

A 1:17 ratio means 1 part coffee to 17 parts water. If coffee is the known amount, water is coffee times 17. If water is the known amount, coffee is water divided by 17. The calculator reports coffee amount in grams, water amount in milliliters, the selected ratio, and a recommended grind size: medium for pour over or drip, coarse for French press, and extra coarse for cold brew. Those outputs are recipe targets, not flavor guarantees, so keep notes when changing beans, roast level, grinder setting, or brew device. Small written notes make the next adjustment easier.

Use this page when setting the dry brew recipe. For a related drink-planning view, see the coffee ratio calculator, and for caffeine context see the coffee calculator. If you are fitting a latte, breakfast, or snack into a food target, pair your drink with the meal calorie calculator or maintenance calorie calculator.

Formula

For a ratio of 1 to R, the calculator uses:

$\text{water} = \text{coffee} \times R$

Or, when water is the known amount:

$\text{coffee} = \frac{\text{water}}{R}$

The variable R is the selected ratio number: 17, 15, 11, 8, or 5 depending on method and strength. the calculator converts the input unit before applying the ratio. Grams and milliliters use a conversion of 1, ounces use 28.3495, and cups use 236.588.

Worked example that matches the calculator

Because coffee is the known amount, the calculator multiplies by 17:

$\text{water} = 30 \times 17 = 510$

The result is 30.0 g coffee, 510.0 ml water, 1:17, and Medium grind. If the same 30 g were used for strong French press, the ratio would be 1:11 and the water amount would be 330.0 ml with a coarse grind recommendation.

For a water-first example, 500 ml water with regular cold brew uses R of 8:

$\text{coffee} = \frac{500}{8} = 62.5$

The calculator would return 62.5 g coffee and 500.0 ml water.

Interpreting ratios by brew method

Pour over and drip methods usually taste balanced near 1:15 to 1:17 because water passes through a bed of medium-ground coffee for a relatively short time. If the cup is thin, try a little more coffee, a slightly finer grind, or better water distribution. If it is bitter and drying, try a coarser grind, slightly less coffee, or a shorter drawdown.

French press uses immersion, so all grounds sit in the water together. the calculator’s regular 1:17 setting is moderate, while 1:11 is rich. Because a metal filter allows more oils and fine particles through, French press can taste heavier than paper-filtered coffee at the same ratio.

Cold brew ratios are stronger because the brewed concentrate is often diluted with water, milk, or ice. A 1:5 cold brew is intense; a 1:8 batch is gentler. Coarse grinding helps limit sludge and over-extraction during the long steep.

Limitations and common mistakes

The calculator does not adjust for water retained in the grounds, ice melt, bypass water, concentrate dilution, or final beverage volume. It also does not know roast level, bean density, grinder quality, filter thickness, water mineral content, or brew temperature. Those details affect extraction and flavor even when the selected ratio is unchanged.

A current behavior to note: the unit conversion is generic. Ounces are converted as 28.3495, and cups as 236.588, then the ratio is applied. That is workable for kitchen approximations, especially water, but coffee volume measurements are less reliable than weighing beans. For repeatable brewing, use grams for coffee and grams or milliliters for water.

Sources

• National Coffee Association, How to brew coffee — general brewing guidance for ratios, water, grind, and freshness.
• Specialty Coffee Association, Coffee standards — professional coffee standards and brewing reference context.
• USDA, FoodData Central — nutrient and beverage data context for coffee entries.