Coffee Ratio Calculator

Enter your coffee dose and a brew ratio to get the exact amount of water to use — or pick a brew method for a sensible default ratio.

Quick Facts

Method
Water (g) = Coffee dose (g) × Ratio
A direct multiplication by weight — no scenario modeling involved. 1g of water is treated as 1ml.

Your Results

Calculated
Water needed
-
Grams (≈ milliliters)
Total brewed weight
-
Coffee + water combined
Ratio used
-
Coffee : Water

Ready

Enter a coffee dose and ratio, then calculate.

How the coffee ratio calculator works

Coffee strength is controlled by the ratio of coffee (by weight, in grams) to water (by weight, in grams — which is essentially the same as milliliters, since water is close enough to 1g/ml at brewing temperatures). The formula is simple: Water (g) = Coffee dose (g) × Ratio. Enter your coffee dose and a ratio (or pick a brew method to auto-fill a typical ratio), and the calculator multiplies them to tell you exactly how much water to add.

The golden ratio

Most immersion and pour-over methods target 1:15 to 1:17 (coffee:water by weight) — 1g of coffee per 15–17g of water. The Specialty Coffee Association's historical "golden ratio" guidance sits around 1:16 to 1:18. Espresso is a different animal, running roughly 1:2 (an 18–20g dose pulling a 36–40g shot). Cold brew concentrate uses far less water relative to coffee, around 1:8, because it is meant to be diluted before drinking.

Worked example

A standard pour-over cup: 20g of coffee at a 1:16 ratio needs 20 × 16 = 320g of water, for a total brewed weight of 340g. Scale linearly — 30g of coffee at the same ratio needs 30 × 16 = 480g of water.

Extraction and strength

  • Under-extracted: sour, salty, thin. Fix with a finer grind, longer contact time, or hotter water — not just a stronger ratio.
  • Over-extracted: bitter, astringent, harsh. Fix with a coarser grind, shorter contact time, or cooler water.
  • Water temperature: 90–96°C (195–205°F) for most hot-brew methods; espresso machines typically run 90–94°C (195–201°F).
  • Ratio vs. extraction: ratio controls concentration (how much coffee is dissolved per cup); grind size, time, and temperature control extraction yield (what percentage of the grounds' soluble compounds end up in the cup). Getting the ratio right does not automatically fix a poorly extracted brew, and vice versa.

Cold brew is different

Cold brew concentrate uses a coarse grind steeped in cold or room-temperature water for 12–24 hours at roughly a 1:8 ratio, then is typically diluted 1:1 with water or milk before drinking. The lower temperature slows extraction dramatically, which is why it needs many more hours than a hot brew — but it also pulls fewer bitter compounds, giving a smoother, less acidic cup.

Frequently Asked Questions

What coffee-to-water ratio should I use?
For drip or pour-over, start at 1:16 (e.g., 20g coffee to 320g water) and adjust up to 1:15 for a stronger cup or down to 1:17 for a milder one. French press typically uses a slightly heavier 1:14 to 1:15 ratio because more fines are retained in the cup. Espresso uses roughly 1:2, and cold brew concentrate uses roughly 1:8.
Is 1g of water really the same as 1ml?
Close enough for brewing purposes. Water's density is almost exactly 1.00 g/ml at room temperature (0.998 g/ml at 20°C) and about 0.96 g/ml near boiling. The difference is under 4% even at the hottest brewing temperatures, which is smaller than the error most kitchen scales and pour techniques introduce — so grams and milliliters are treated interchangeably in brewing.
Why weigh coffee and water instead of using scoops or cups?
A "tablespoon" of coffee can vary by 30% or more depending on grind size, roast density, and how it's scooped. A kitchen scale removes that variability, which is why baristas and home-brewing guides specify ratios by weight rather than volume.
Does this calculator account for grind size or brew time?
No — this tool computes the coffee-to-water ratio only. Grind size, water temperature, and contact time affect extraction (how much flavor is pulled from the grounds), which is a separate variable from ratio (how concentrated the final cup is). Two cups can share the same ratio and still taste very different if one is under- or over-extracted.

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