Coffee Ratio Master
Precision brewing calculator for coffee perfectionists.
Interactive Brew Timer
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What this calculator does
Coffee Ratio Master works out how many grams of coffee and how much water you need for the amount of coffee you want to brew. It also suggests a grind size and water temperature for your brew method, and has a brew timer that tells you what to do at each stage of a pour over, Chemex or French press.
How to use it
- Pick your Brew Method. The strength slider moves to that method's usual starting ratio.
- Enter how much coffee you want and choose oz (US fluid ounces), ml or Cups (8 oz US measuring cups).
- Move the strength slider if you like your coffee stronger (toward 1:12) or milder (toward 1:18).
- Weigh out the Coffee Beans and Water Needed shown, grind to the suggested size and heat the water.
- Press Start Brew when the water first touches the coffee.
How it's calculated
A brew ratio of 1:16 means 1 gram of coffee for every 16 grams of water. Because 1 mL of water weighs about 1 gram, the tool can work in milliliters:
coffee (g) = water (mL) ÷ ratio
For example, 12 oz of water is 355 mL, and 355 ÷ 16 = 22 g of coffee.
The amount you enter is the water you pour. The grounds hold back some water (roughly twice their own weight), so the finished cup is a little smaller. If you need an exact cup size, add about 12% to the amount at 1:16 (a little more at stronger ratios).
Starting points by method
| Method | Ratio | Grind | Water temperature |
|---|---|---|---|
| Drip machine | 1:16 | Medium | 200 °F (93 °C) |
| Pour over (V60, Kalita) | 1:16 | Medium-fine | 205 °F (96 °C) |
| French press | 1:15 | Coarse | 200 °F (93 °C) |
| Chemex | 1:16 | Medium-coarse | 205 °F (96 °C) |
| AeroPress | 1:12 | Fine | 195 °F (91 °C) |
| Cold brew (concentrate) | 1:5 | Extra coarse | Room temperature |
What the "golden ratio" really is
The Specialty Coffee Association's Golden Cup standard for filter coffee is 55 grams of coffee per liter of water, which works out to about 1:18, brewed with water between 90 and 96 °C (194–205 °F). Many people find that a little weak, so most home recipes, and this tool, start at 1:15 to 1:16. Treat any ratio as a starting point and adjust to taste.
Adjusting for taste
- Sour, thin or salty: under-extracted. Grind finer, use hotter water, or brew a little longer.
- Bitter, harsh or drying: over-extracted. Grind coarser or shorten the brew.
- Tastes fine but too weak: use more coffee, so move the slider toward 1:15.
- Tastes fine but too strong: use more water, so move the slider toward 1:17.
Change one thing at a time so you know which change made the difference.
Using the brew timer
- Pour over and Chemex: for the first 45 seconds, pour about twice the coffee's weight in water and let it "bloom" (release gas). Pour the rest in slow circles until 2:00, then let it drain, ideally finishing by about 3:00.
- French press: stir during the first minute so all the grounds get wet, put the lid on and steep until 4:00, then press the plunger down slowly.
- Other methods: the timer simply counts up.
Frequently asked questions
Why weigh coffee instead of using scoops?
Beans differ in density, so a scoop of one coffee can weigh noticeably more or less than a scoop of another. A kitchen scale that reads to 1 gram gives the same cup every morning.
Why doesn't my coffee maker's "cup" match?
Many drip machines mark their carafes in 5 or 6 oz "cups". In this tool, Cups means an 8 oz US measuring cup. To brew a full carafe, enter the carafe's capacity in oz or mL instead.
How do I serve cold brew concentrate?
At 1:5 it's too strong to drink straight. Dilute it with water or milk, often about 1 part concentrate to 1 part water, and adjust to taste.
Does grind size change the ratio?
No, but it changes how fast coffee extracts. Finer grinds extract quickly and suit short brews; coarse grinds suit long steeps like French press and cold brew.
Sources: Specialty Coffee Association, SCA Standard 310-2021: Home Coffee Brewers (Golden Cup brew ratio and temperature). Last reviewed on SuiteWebTools: October 2026.