What this calculator does
A brew ratio is grams of water to grams of coffee, written as 1:16 or similar. Because a millilitre of water weighs almost exactly a gram, 500 ml of water at 1:16 needs 31.3 g of grounds, and the whole calculation is one division. Ratios between about 1:15 and 1:17 are the usual starting range for filter coffee.
The figure people forget is absorption. Wet grounds hold roughly twice their own weight in water and keep it, so 500 ml of water poured over 31.3 g of coffee yields about 438 ml in the cup, not 500. If you need a specific volume brewed, work backwards from it rather than from the water you pour.
The formula
The grounds needed are the water volume divided by the ratio, taking 1 ml of water as 1 g. The brewed yield subtracts twice the weight of the grounds, which is the water they retain and you never pour out. The tablespoon figure uses about 5 g per level tablespoon of ground coffee, which is a rough conversion because grind size and bean density both change it.
| Term | Meaning |
|---|---|
| Brew ratio | Parts water to one part coffee by weight, written 1:16 and read as sixteen grams of water per gram of coffee. |
| Dose | The weight of dry grounds used. |
| Absorption | Water retained by the spent grounds, roughly twice their dry weight, which never reaches the cup. |
| Yield | The brewed volume actually produced, after absorption is taken out. |
The inputs explained
| Field | What to enter |
|---|---|
| Water (ml) | The water you are brewing with, in millilitres. Taken as grams at one to one, which is accurate enough at brewing temperature. |
| Ratio (1 : n) | The second number of the ratio. Lower is stronger: 14 is a strong brew, 16 is standard, 18 and above is light. |
| Cups it makes | How many cups you are dividing it into, used only for the per-cup figures. |
When to use it
Scaling a recipe to the water you have
Brewing devices come in fixed sizes, so the water volume is usually the fixed quantity and the dose is what has to be worked out. That is the direction this calculator runs in.
Dialling a brew in stronger or weaker
Changing one variable at a time is the only reliable way to adjust a brew. Holding the water fixed and moving the ratio shows exactly how much the dose has to change for a noticeable difference.
Hitting a target brewed volume
If you need a specific amount in the pot, the yield line matters more than the water line. Absorption takes out roughly twice the dose, so you pour more water than you get back.
Worked examples
Every figure in the tables below is produced by this page’s own calculator at build time, so the numbers and the tool always agree. Select any row to load that scenario.
How much coffee does each brew ratio need?
A fixed 500 ml of water across the range of ratios from strong to light.
| Ratio | Coffee grounds | Level tablespoons (≈5 g) | Brewed yield after absorption | Strength |
|---|---|---|---|---|
| 1:12 | 41.7 g | 8.3 | 417 ml | Strong |
| 1:14 | 35.7 g | 7.1 | 429 ml | Standard |
| 1:15 | 33.3 g | 6.7 | 433 ml | Standard |
| 1:16 | 31.3 g | 6.3 | 438 ml | Standard |
| 1:18 | 27.8 g | 5.6 | 444 ml | Light |
| 1:20 | 25.0 g | 5.0 | 450 ml | Light |
Questions
What is the best coffee to water ratio?
For filter coffee, somewhere between 1:15 and 1:17 is the usual starting point, with 1:16 the most common single answer. Espresso runs far tighter, around 1:2. There is no correct figure, only a range most people find balanced, and moving within it is the fastest way to find what you prefer.
Can I measure in millilitres rather than grams?
For the water, yes, since a millilitre weighs essentially a gram. For the coffee, not reliably. Ground coffee varies in density with the bean and the grind, so a tablespoon can hold anywhere from about 4 to 7 grams. Scales are the single change that most improves consistency.
Why do I get less coffee out than water in?
Because the grounds keep some. Spent coffee retains roughly twice its dry weight in water, so a 31 g dose holds back about 62 ml. It is the reason a brew aimed at filling a specific pot needs more water poured than the pot holds.
Does the ratio change for cold brew?
Yes, substantially. Cold brew concentrate is commonly made between 1:4 and 1:8, then diluted before drinking. Entering one of those ratios here gives the dose for the concentrate, and the absorption figure becomes a larger share of the total because the dose is so much bigger.
For scaling a recipe by servings rather than by ratio, see the recipe scaler. For concentrate-to-water ratios generally, see the dilution ratio calculator.