Hong Life CalculatorsUnderstanding the coffee brew ratio calculator — concept and principle
The brew ratio is the weight of ground coffee compared with the weight of water, written as 1 : N. It is the first thing to fix when coffee tastes too weak or too strong, and it lets you scale a recipe from one cup to a full carafe. Choose a brewing method and the amount of water, and the calculator returns the dose of coffee to weigh out.
How it is calculated
Coffee (g) = water (g) ÷ N, where N is the ratio of the selected method.
- Pour-over / filter 1:16, French press 1:15, batch brewer 1:17.
- Cold brew concentrate 1:8 (usually diluted before drinking).
- Espresso 1:2: here "water" means the weight of liquid espresso in the cup, so 36 g of espresso needs an 18 g dose.
Because 1 mL of water weighs about 1 g, grams and millilitres can be used interchangeably for the water.
The principle
Strength (how concentrated the drink is) depends mainly on how much coffee is dissolved per unit of water. The Specialty Coffee Association's "golden cup" guidance for filter coffee is about 55 g of coffee per litre of water (roughly 1:18), with a target of about 18–22 % of the coffee's mass extracted and a strength of roughly 1.15–1.35 % total dissolved solids. Many home brewers prefer slightly stronger ratios like 1:15–1:16. Immersion methods and cold brew use more coffee because extraction is slower or the result is meant to be diluted.
Worked example
Defaults: 500 g water, pour-over 1:16.
- Coffee = 500 ÷ 16.
- = 31.25 g of coffee, ratio 1:16.
| Water (g or mL) | Coffee (g) |
|---|---|
| 125 | 7.81 |
| 250 | 15.63 |
| 375 | 23.44 |
| 500 | 31.25 |
| 625 | 39.06 |
| 750 | 46.88 |
| 1,000 | 62.5 |
How to read the result
A smaller N means stronger coffee. If the cup tastes thin, move toward 1:15; if it is heavy, toward 1:17 or 1:18. Ratio controls strength, while grind size, time and water temperature mainly control extraction: sour and sharp often means under-extracted, bitter and drying often means over-extracted. Change one variable at a time. Remember that wet grounds hold back roughly twice their weight in water, so the drink in the cup is less than the water you pour.
Common mistakes
- Measuring coffee by scoops; density varies with roast and grind.
- Fixing bitterness by changing the ratio when the grind is the real issue.
- Treating cold brew concentrate as ready to drink without dilution.
Frequently asked questions
How many grams of coffee for one mug?
For a 250 mL mug at 1:16, about 15–16 g.
Is espresso ratio about water in?
No. Espresso ratios compare dose to beverage weight out, so weigh the shot.
How do I dilute cold brew concentrate?
Often about 1 : 1 with water or milk, then adjust to taste.
Sources: Specialty Coffee Association — Brewing Control Chart and Golden Cup standard. · Scott Rao, Everything but Espresso (self-published).