How the coffee ratio calculator works
A brew ratio is grams of water for every gram of coffee. 1:16 means 16 g of water for each gram of grounds. Weight is what matters, and a milliliter of water weighs about a gram, so the calculator treats them as the same.
1. Pick a method and its starting ratio
Each method starts at a ratio from its published range (AeroPress is the exception, see below). Change the ratio to make it stronger (lower) or weaker (higher).
| Method | Starts at | Published range |
|---|---|---|
| Pour over | 1:16 | 1:13 to 1:16 (NCA) |
| Drip coffee maker | 1:18 | 1:18 (SCA, Starbucks) |
| French press | 1:15 | 1:10 to 1:16 (NCA) |
| AeroPress | 1:12 | 16 to 18 g to the 4 mark (AeroPress) |
| Cold brew concentrate | 1:5 | 1:4 to 1:5 (NCA) |
| Cold brew, ready to drink | 1:5 | 1:5, then diluted 1:1 |
| Espresso | 1:2 | 1:2 coffee to espresso (NCA) |
2. Say how much you want
Enter cups, mugs, ounces, milliliters or the grams of coffee you have. If the amount is what you want to drink, the calculator adds back the water the grounds keep. A UC Davis study of immersion brews measured about 2.5 g of liquid left in the spent grounds for every gram of coffee (2.48 on average), so a 12 ounce mug needs more than 12 ounces of water.
3. Read the coffee, water and bloom
Coffee = water ÷ ratio. Tablespoons assume about 5 g per level tablespoon, from Starbucks' 2 tablespoons (10 g) per 6 fl oz. For pour over, the NCA says to bloom with about double the coffee's weight in water and wait 30 to 45 seconds before pouring the rest. For cold brew, the ready-to-drink option brews a 1:5 concentrate and dilutes it 1:1, as the Toddy guide does.
Worked example
One 12 fl oz mug of pour over at 1:16. The mug holds 355 ml. The grounds keep about 2.5 g of water per gram, so each gram of coffee leaves 13.5 g in the cup. That takes 355 ml ÷ 13.5 = 26.3 g of coffee, about 5½ tbsp. Brew with 421 g of water (14.2 fl oz), starting with a 52.6 g bloom.
A drip machine filled to twelve 6 fl oz cups uses 2,129 ml of water. At 1:18 that is 118 g of coffee, about 23½ tbsp (1½ cups), and about 62 fl oz of coffee in the carafe.
For a liter of ready-to-drink cold brew, steep 200 g of coarse coffee in 1,000 ml of water. That gives about 500 ml of concentrate. Add 500 ml of water or milk.
Where the sources differ
The ranges overlap but don't match. The SCA's home brewer standard uses about 1:18. The NCA's pour-over range runs from 1:13 to 1:16, which is stronger, and its French press range is wide, from 1:10 to 1:16. None of them is wrong: they describe different brewers and different tastes. Start in the middle of your method's range and change one thing at a time.
Cups are the other trap. A measuring cup is 8 fl oz, the NCA's golden ratio is per 6 ounces, and Starbucks notes that a coffee maker's cup can be 4 to 6 fl oz. AeroPress gives its recipe as 16 to 18 g with water to the 4 mark and doesn't say how much water that is, so its 1:12 here is a starting point rather than a published number.
Sources
- Specialty Coffee Association: SCA Standard 310-2021, Home Coffee Brewers (55 g per 1.000 kg of water), archived
- National Coffee Association: Drip coffee (golden ratio)
- National Coffee Association: Pour-over coffee (ratio and bloom)
- National Coffee Association: French press coffee
- National Coffee Association: Cold brew coffee
- National Coffee Association: Espresso
- AeroPress: How to use (16 to 18 g recipe)
- Starbucks at Home: Coffee machine brewing guide (10 g, 2 tbsp per 6 fl oz)
- Seattle Coffee Gear: Toddy Cold Brew System guide (dilution)
- Liang, Chan and Ristenpart (UC Davis), Scientific Reports 2021: liquid retained by spent grounds