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Strike water temperature calculator

Strike temperature = (0.41 ÷ ratio in L/kg) × (target mash °C − grain °C) + target mash °C. Grain at 20 °C, a 67 °C mash and 3 L/kg need strike water at about 73.4 °C (164.2 °F).

BrewMyBeer Editorial Team · Sources checked 24 September 2026 · Calculated examples, not laboratory measurements. How we create content

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Measure the grain where it has been stored; 20 °C is 68 °F.

The rest temperature in your recipe; 67 °C is 152.6 °F.

Litres of strike water per kilogram of grain; 1 qt/lb is about 2.09 L/kg.

Used only to show the volume of strike water to heat.

Why the water must start hotter than the mash

Grain added to the water starts cooler than the mash you want, so the water has to carry extra heat to bring both to the target. The colder the grain and the less water per kilogram, the more extra heat each litre must carry.

Home Brew Answers gives the metric form used here, Tw = (0.41 ÷ R)(T2 − T1) + T2, with a worked example: 4 kg of grain at 18 °C in 10 L of water (2.5 L/kg) for a 67 °C mash needs 75 °C water. The calculator reproduces that result.

Metric and US units use different constants

In US units, with the ratio in quarts per pound and temperatures in °F, the same source says the constant is 0.2 instead of 0.41. The two agree: one quart per pound is about 2.09 L/kg, and 0.2 × 2.09 ≈ 0.41. Never mix the metric constant with US units.

Brewer’s Friend says its strike calculator is based on John Palmer’s equation, that it works best for batch sparging, and that it assumes your tun absorbs heat. It advises not to preheat the tun to the strike temperature and then add grain, because you will probably overshoot.

Hitting the number on brew day

Treat the result as a starting point. Brewer’s Friend suggests padding the strike temperature by up to about 5.5 °C (10 °F) in a cold setting, and says it can take a couple of brew days to dial in your equipment.

Stir thoroughly to break up dough balls, wait a few minutes, then take readings in more than one place before deciding to add hot or cold water.

Before you use the result

  • Use the same ratio you will actually mash with, in L/kg.
  • Measure the grain temperature, not the room temperature.
  • Confirm the mash temperature with a calibrated thermometer after stirring.
  • For adults of legal drinking age. This tool describes a batch or a beer, not its effect on a person.

A quick learning check

If you mash thicker, with less water per kilogram, what happens to the strike temperature?

Try a craft decision game →

Sources & further reading

These references explain the methods and limitations. The worked examples and learning questions on this page are BrewMyBeer calculations, not claims of hands-on testing.