About the Strike Water Calculator
This strike water calculator tells all-grain homebrewers how hot to heat their mash water — the strike water — and how much of it to use, so that the mash settles at the target temperature once the grain is stirred in. Cool grain absorbs heat from the water, so the strike temperature always has to be higher than the mash temperature you want.
Enter the grain bill weight, the water-to-grain ratio, the temperature of the grain (usually room temperature) and your target mash temperature, in US units (quarts per pound, °F) or metric (litres per kilogram, °C). You get the strike temperature, the strike water volume and the total volume the mash will occupy, so you can check it fits in your mash tun.
Mash temperature shapes the beer: around 148–150°F (64–66°C) gives a drier, more fermentable wort, 152–156°F (67–69°C) a fuller body. The formula assumes a preheated mash tun; if your cooler or kettle starts cold, add a few degrees with the equipment adjustment, or preheat it with hot water first.
How to use the strike water calculator
- 1Choose US or metric units.
- 2Enter the total grain bill weight and your water-to-grain ratio.
- 3Measure the grain temperature and enter your target mash temperature.
- 4Add a few degrees if your mash tun is not preheated.
- 5Heat the strike water, add the grain, stir well and check the temperature.
Formula and method
This is John Palmer’s infusion equation from How to Brew. It balances heat: the water cools from Tw to the mash temperature T2 while the grain warms from T1 to T2. The constant 0.2 (US) or 0.41 (metric) is the specific heat of grain relative to water, about 0.4, converted for quarts per pound or litres per kilogram. A thinner mash (larger r) needs a smaller temperature boost.
Strike volume is grain weight × ratio. The total mash volume adds the space taken by the grain, about 0.32 quarts per pound (0.67 L per kg), so you can check your mash tun capacity. The equipment adjustment is simply added on top for an unheated tun.
- Tw
- Strike water temperature
- T1
- Grain temperature
- T2
- Target mash temperature
- r
- Water-to-grain ratio
Worked examples
10 lb grain bill at 1.5 qt/lb
With 65°F grain and a 152°F target: (0.2 ÷ 1.5) × 87 + 152 = 163.6°F. Ten pounds at 1.5 qt/lb needs 15 qt (3.75 gal) of water, and the full mash occupies about 3.75 + 0.8 = 4.55 gal.
Metric: 5 kg at 3 L/kg, mash at 66°C
(0.41 ÷ 3) × (66 − 20) + 66 = 72.3°C. Five kilograms at 3 L/kg uses 15 L of water, and the grain adds about 3.3 L, for a mash of roughly 18.3 L.
Thick mash in a cold cooler
(0.2 ÷ 1.25) × 84 + 154 = 167.4°F, plus 2°F for the unheated cooler gives 169.4°F. Twelve pounds at 1.25 qt/lb is 15 qt of water; the mash fills about 4.7 gal.
Frequently asked questions
What is strike water?+
Strike water is the hot water you mix with crushed grain at the start of an all-grain mash. It is heated above the target mash temperature because the cooler grain absorbs heat as the two are combined.
What water-to-grain ratio should I use?+
Most infusion mashes use 1.25–2 quarts per pound (2.6–4.2 L/kg). Around 1.5 qt/lb is easy to stir and works well in coolers; brew-in-a-bag uses the whole batch volume and so is much thinner.
What mash temperature should I aim for?+
Around 148–150°F (64–66°C) favors beta-amylase and a dry, highly fermentable wort; 154–156°F (68–69°C) favors alpha-amylase and a fuller-bodied, sweeter beer. 152°F (67°C) is a common middle ground.
Why did my mash come in too low?+
Usually an unheated mash tun soaked up heat, or the grain was colder than entered. Preheat the tun with hot water, or add a few degrees with the equipment adjustment next time.
How do I fix a mash that is too hot or too cold?+
Stir in small amounts of cold water (or ice) to bring it down, or near-boiling water to raise it, checking after each addition. Correct within the first few minutes, before enzymes do most of their work.