Coffee Water Temperature by Roast Calculator
Get the recommended brew-water temperature for your roast level, in both Celsius and Fahrenheit, with a sensible working range.
How it works
°F = °C × 9/5 + 32 · Lighter roasts brew hotter, darker roasts cooler
Hotter water extracts faster and more completely, which is why the roast level should steer your temperature. Light roasts are dense and harder to extract, so they favor near-boiling water (96–99 °C) to avoid a sour, underdeveloped cup. Darker roasts are more soluble and prone to bitterness, so cooler water (85–90 °C) keeps them smooth. The broadly cited all-purpose window is 90–96 °C — never actually boiling on the grounds.
Worked example
For a light roast the midpoint recommendation is about 97 °C, which is 97 × 9/5 + 32 ≈ 207 °F — just off the boil.
Frequently asked questions
Should I pour boiling water on coffee?
Generally no. Water right at 100 °C can scald the grounds and pull out bitterness, especially on darker roasts. Let a kettle rest 30–45 seconds off the boil, or use a variable-temperature kettle set to the range for your roast.
Why do darker roasts use cooler water?
Roasting makes coffee more soluble, so dark roasts give up their solids readily. Cooler water slows extraction just enough to keep the cup from turning harsh and bitter.
Does temperature matter as much as ratio?
Ratio and grind usually have the biggest effect, but temperature is a real lever — a 5 °C change noticeably shifts the balance between sour and bitter. Dial in ratio and grind first, then fine-tune temperature.
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This calculator is for educational purposes. Double-check important results before acting on them.