Coffee Ratio & Brew Calculator
Enter the dose per cup, the number of cups and the ratio to get total water, bloom water, the coffee actually left in the cup, and a pour schedule with grind, temperature and time.
The ratio tells you how much water to pour. It does not tell you whether the cup tastes good — grind, temperature and time do that. Enter the dose per cup, the number of cups and the ratio; the page returns the total water, the bloom, the coffee you actually get in the cup, and a pour schedule for the brewer you are using.
Your brew
Weigh the coffee. A 0.1 g scale matters more than any fancy dripper.
1 : water ÷ coffee. 15–17 for pour-over; 12 for iced or milk drinks.
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Ratio quick reference
| Ratio | Water for 15 g | Body | Best for |
|---|---|---|---|
| 1:12 | 180 ml | Heavy, syrupy | Milk or iced drinks |
| 1:15 | 225 ml | Balanced | Everyday cup |
| 1:16 | 240 ml | Clean, light | Standard pour-over |
| 1:17 | 255 ml | Aromatic, tea-like | Light roasts |
| 1:18 | 270 ml | Thin | Large mugs, cold brew dilution |
Brewer settings
| Brewer | Grind | Water temperature | Total time | Suggested ratio |
|---|---|---|---|---|
| V60 / pour-over | Medium-fine — like table sugar | 92–94°C | 2:30–3:00 | 1:15–1:17 |
| French press | Coarse — like sea salt | 92–94°C | 4:00 steep | 1:15–1:17 |
| AeroPress | Medium-fine | 85–90°C | 1:30 | 1:13–1:16 |
| Cold brew | Extra coarse | Cold water | 12–16 hours | 1:8–1:10 concentrate |
Five things the ratio does not tell you
- The ratio sets the ceiling of strength, not the flavour. Grind, water temperature and contact time decide how much you extract.
- Coffee grounds hold about twice their weight in water. A 15 g dose with 240 g of water leaves roughly 210 g in the cup, not 240.
- Bloom with twice the dose of water for 30 seconds. It releases CO₂ so the first real pour wets evenly instead of channelling.
- Fix the dose first, then move the water. Changing both at once makes it impossible to know which change helped.
- For iced coffee, replace 30–40% of the water with ice. The ice melts into the brew, keeping the strength close to the hot version.
Practical notes
- Light roasts like hotter water, 93–95°C; dark roasts turn bitter and ashy above 90°C.
- Grind consistency beats grind size. A cheap blade grinder makes both boulders and dust, and the cup tastes muddy.
- Write down dose, water, grind and time. One change per brew is the fastest way to learn what you like.
- For milk drinks, brew at 1:12 so the coffee still tastes like coffee after the milk goes in.
Four common mistakes
- Scooping with a tablespoon. Volume varies with roast and grind; only a scale gives a repeatable dose.
- Pouring the full water weight and expecting the same weight in the cup. Grounds keep about 2 g of water per gram.
- Letting the bloom run for minutes. The bed cools, and the rest of the pour extracts unevenly.
- Making cold brew at 1:16 and then diluting it again. Cold brew concentrate is 1:8–1:10; dilute at serving, not twice.
Taste is personal. These numbers are a starting point, not a rule; adjust one variable at a time. Drink caffeine in moderation.