Strike water calculator
Cold grain cools the water it is mixed with, so the strike water has to start hotter than the mash. Enter the grain weight, how thick you mash, the grain temperature and the mash temperature you want. The calculator gives the strike water temperature and volume and how much room the mash takes in the tun.
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How to use
- Choose kilograms, liters and °C or pounds, quarts and °F.
- Enter the grain weight and the water-to-grain ratio you want.
- Enter the grain temperature (usually room temperature) and the target mash temperature.
- Heat that much water to the strike temperature, add it to the grain and stir.
How it works
Strike temperature: Tw = (0.2 ÷ r) × (T₂ − T₁) + T₂, with r in qt/lb, T₁ the grain and T₂ the target temperature. Metric ratios are converted with 1 L/kg = 2.086 qt/lb; because the formula works with differences, it gives the right answer in °C or °F. Strike volume = grain × ratio. Mash volume = strike volume + grain × 0.32 qt/lb (0.668 L/kg).
Example
10 lb of grain at 70 °F, 1.5 qt/lb, target 152 °F:
- Tw = (0.2 ÷ 1.5) × (152 − 70) + 152 = 0.1333 × 82 + 152 = 162.9 °F;
- strike water 10 × 1.5 = 15 qt, which is 3.75 gal;
- mash volume 15 + 10 × 0.32 = 18.2 qt, about 4.55 gal.
Tips
- Overshooting is easier to fix than undershooting: stir in a little cold water if the mash is too hot, or keep some near-boiling water ready if it is too cold.
- Check the temperature in several places after stirring and wait a minute for it to settle.
- For step mashes and mash-out, each later infusion needs its own calculation from the current mash temperature.
Frequently asked questions
How do you calculate strike water temperature?
With the usual infusion formula Tw = (0.2 ÷ r) × (T₂ − T₁) + T₂, where r is the water-to-grain ratio in quarts per pound, T₁ the grain temperature and T₂ the target. The 0.2 is the heat capacity of grain relative to water. In liters per kilogram the constant becomes 0.2 × 2.086 = 0.417.
What water-to-grain ratio should I use?
Many brewers mash at 2.5 to 3.5 L/kg (1.2 to 1.7 qt/lb). A thicker mash needs hotter strike water for the same target; a thinner one is easier to stir and suits brew-in-a-bag, where all the water goes in at once.
Why did my mash come out too cold?
The formula assumes the tun is already warm. A cold cooler or kettle soaks up heat, so preheat it with hot water or add a couple of degrees the first time and note the result. Stirring well matters too: a single reading in a pocket of grain can be off by several degrees.
What is the mash volume for?
To check that the grain and water fit in your mash tun. Grain takes up about 0.32 qt per pound (0.67 L per kg) on top of the water, so 15 L of water with 5 kg of grain fills about 18.3 L.