Coffee brew ratio calculator
How much coffee a volume of water takes at a chosen brew ratio.
Fill in the fields and the result will appear here automatically.
Solves the brewing equation in either direction: coffee dose for an input water volume, water for a dose, or the ratio from both known quantities. Here 1:16 means 1 g of dry coffee per 16 mL of water supplied for brewing. It is not a brewed-beverage mass ratio or the volume left in the cup after filtration. Unlike scaling a whole ingredient list by servings, this tool relates two quantities. Grind, contact time and brewing method also influence strength and taste.
How it works
Formula and logic
Water mL = coffee g × k; coffee = water ÷ k; k = water ÷ coffee. Both known values must be positive; the solved field is ignored as an input. k has units of mL water per g coffee. Water volume is not converted to mass using temperature. The extra grounds row assumes a capacity of 2 mL/g, rather than measuring water loss or exact beverage yield.
Example
500 mL of input water at 1:16 needs 31.25 g coffee. Conversely, 30 g with 480 mL gives 1:16. At 30 g and k = 1, water is 30 mL; the assumed grounds capacity of 60 mL does not mean that 60 mL actually disappear from those 30 mL.
Fields and units
- What to find — list option
- Water, ml — mL
- Coffee, g — g
- Ratio 1:k — mL/g
How to use
- — Choose the unknown: coffee, water or k.
- — Enter the two known values; the unknown input is hidden and its answer appears in the result.
- — Use the recipe’s input water, not finished cup volume.
- — Choose a recipe and equipment ratio; grounds capacity cannot replace a measurement of beverage yield.
Method and limitations
- Calculation method
- Formula and logic
- Data or methodology source
- Moccamaster: an input-water recipe example adjustable to taste; does not validate 1:16 or grounds capacity of 2 mL/g
- Limitation
- The model calculates input proportions and an assumed capacity; it does not measure extraction, beverage strength or finished yield.
FAQ
Which ratio should I use?
Use your recipe or equipment instructions and compare taste under comparable conditions. The retained 1:16 is a calculation example, not a requirement for every brewing method.
Why is there less in the cup than water poured?
Grounds and filters can retain water. The 2 mL/g figure here is an assumed grounds capacity, without measuring actual retention, evaporation or cup yield.
How is this different from scaling a recipe?
Recipe scaling multiplies a whole ingredient list by a serving factor. Here one relationship connects dry coffee dose and input water volume; any variable can be found from the other two.
Grams or millilitres for water?
These fields use mL of water and g of coffee. If your recipe specifies water mass, convert it for the measurement conditions or use a mass-based calculation elsewhere. No universal error below 3% is guaranteed.