Coffee to Water Ratio Calculator
Scale a coffee recipe by brew method, strength, ratio, water volume, or coffee mass while keeping the recipe mathematically consistent.
Recipe inputs
Edit either water or coffee; the most recently edited amount becomes the scaling input and the other amount is recalculated.
Live recipe
Scaled recipe
360.0 mL water for 20.0 g coffee
General, Regular preset, ratio 1:18.
Coffee-to-water ratio
1:18
1 part coffee to 18 parts water by approximate mass.
Coffee per liter
55.56 g/L
Equivalent dose for 1 liter of water.
Water
360.0 mL
12.17 US fl oz · 1.52 US cups
Coffee
20.0 g
0.71 oz
Recipe details
| Component | Selected amount | Metric equivalent | US customary equivalent |
|---|---|---|---|
| Coffee | 20.0 g | 20.0 g | 0.71 oz |
| Water | 360.0 mL | 360.0 mL | 12.17 US fl oz · 1.52 US cups |
How to use this coffee to water ratio calculator
What this calculator does. This tool scales a brewing recipe from a coffee-to-water ratio. It converts between a measured coffee mass and a water volume using the practical brewing approximation that 1 mL of water is about 1 g. It is designed for recipe planning, not for predicting extraction yield, dissolved solids, final beverage volume, caffeine content, or subjective flavor. A ratio is a repeatable starting point; grind, temperature, water chemistry, contact time, roast, and brewer design still affect the cup.
When to use it. Use it when you want to scale a favorite recipe up or down, compare a regular and stronger brew, translate a metric recipe into U.S. kitchen units, or find how much coffee is needed for a known quantity of water. It is also useful for documenting a repeatable batch before you begin adjusting grind or brew time.
How to calculate. The calculator opens with a complete demonstration: General brew type, Regular strength, ratio 1:18, 20.0 g coffee, and 360.0 mL water. The example workbook is immediately available from Download Excel. To make your own recipe:
- Choose Brew type and Strength if you want a preset. Changing either control writes its preset into Ratio denominator.
- Edit Ratio denominator directly when you want a custom recipe. For a 1:16 ratio, enter 16.
- Enter either Amount of coffee or Amount of water. The last amount you edit becomes the scaling input, and the other amount updates automatically.
- Use Coffee unit or Water unit to switch units. The current quantity is converted rather than merely relabeled.
- Read the live recipe, the ratio, coffee dose per liter, converted water and coffee amounts, and the Recipe details table. Then use Download Excel to save the current validated model.
- Use Reset when you want a genuinely blank recipe. Reset clears the demonstration amounts and ratio, returns selectors to their neutral defaults, clears results, and disables Download Excel until you enter a complete valid state again.
Input guide. Brew type is a required select with General, Pour over / drip, French press, and Cold brew presets. For example, General plus Regular starts at 1:18; changing brew type can materially change the suggested ratio. Strength is a required Regular/Strong preset selector; it is only a shortcut, so do not assume it measures sensory strength objectively. Ratio denominator is a required positive decimal from 1 to 100, entered with a period decimal and no scientific notation. A larger denominator means more water per gram of coffee and therefore a lower coffee dose per liter. Amount of water is a positive decimal in mL, US fl oz, or US cups; values are converted exactly enough for kitchen use, and decimal commas such as 1,5 are rejected rather than silently reinterpreted. Water unit controls only the displayed/editable water unit. Amount of coffee is a positive mass in g or oz; 20 g is a realistic single-recipe example. Coffee unit switches between grams and ounces. Do not enter a coffee volume such as tablespoons in the mass field, because grounds pack differently by roast and grind.
Output guide. Scaled recipe states the current water and coffee amounts in the selected units. Coffee-to-water ratio is the exact 1:x recipe identity used by the calculation. Coffee per liter is 1000 ÷ x in g/L; a higher number means a larger coffee dose for the same water volume. Water shows the canonical water quantity and its mL, US fl oz, and US cup conversions; Coffee shows the same coffee mass in grams and ounces. The header pills repeat Brew type, the active preset/custom status, and Ratio so you can verify the recipe at a glance. The Recipe details table has four columns: Component identifies coffee or water, Selected amount uses your current unit, Metric equivalent standardizes to g or mL, and US customary equivalent provides oz, fluid ounces, and cups. These are conversions and mathematical identities, not taste recommendations.
Worked example. The startup recipe uses a 1:18 ratio and 20.0 g of coffee. The model multiplies 20.0 g × 18 = 360.0 g of water, then uses the brewing approximation 1 g water ≈ 1 mL to display 360.0 mL water for 20.0 g coffee. The same ratio corresponds to 1000 ÷ 18 = 55.56 g/L. The 360.0 mL water converts to 12.17 US fl oz and about 1.52 US cups, while 20.0 g coffee converts to about 0.71 oz.
Learn more. The Specialty Coffee Association discusses the distinction between brewing ratio and beverage ratio and gives a commonly used example around 60 g/L in its article on water, acidity, and coffee extraction. SCA brewer certification material has also used 55 g/L as a test coffee-to-water ratio, which is close to this calculator's 1:18 General/Regular demonstration.
How the ratio model works
A coffee-to-water ratio written 1:x means one unit of coffee mass for x equal units of water mass. For ordinary brewing quantities, treating water density as about 1 g/mL makes the calculation convenient: water in mL is approximately coffee in grams multiplied by x. Reversing the equation gives coffee in grams as water in mL divided by x. The calculator keeps those equations in canonical metric units and converts only at the edges of the model, so switching from grams to ounces or from milliliters to fluid ounces does not alter the underlying recipe.
The presets are intentionally starting points rather than universal rules. General Regular uses 1:18 and General Strong 1:15. Pour over / drip uses 1:17 or 1:15, French press uses 1:17 or 1:11, and Cold brew uses 1:8 or 1:5. The wider differences for cold brew reflect a more concentrated recipe style. For formal context on brewing performance and standardized terminology, see the Specialty Coffee Association's coffee standards overview.
Units, water, and practical accuracy
Water and coffee use different kinds of measurement on purpose. Water is naturally convenient to measure by volume, while coffee grounds are more repeatable by mass. The U.S. customary fluid ounce is a volume unit, but the avoirdupois ounce used for coffee here is a mass unit; they should not be interchanged. This calculator uses 29.5735295625 mL per U.S. fluid ounce, 236.5882365 mL per U.S. cup, and 28.349523125 g per ounce. NIST's Metric Kitchen measurement equivalencies provides practical kitchen conversions and explains the distinction between fluid volume and mass units.
The 1 g/mL water assumption is deliberately practical. Actual water density varies slightly with temperature and dissolved minerals, but the difference is generally small compared with normal home-brewing variation. For repeatability, weigh coffee, measure or weigh water consistently, and change one brewing variable at a time. A ratio that tastes weak can be adjusted by lowering the denominator, while a ratio that tastes too concentrated can be adjusted upward. Keep in mind that changing ratio also changes extraction conditions, so grind and contact time may need attention rather than treating ratio as the only flavor control.