Strike Water Temperature Calculator for Mashing

Strike water must be hotter than the target mash temperature to make up for the cooler grain. With grain at 20 °C, a mash of 3 L/kg and a 66 °C rest, heat the strike water to about 72 °C. Thicker mashes and colder grain need hotter water, and so does a mash tun that is not preheated.

How the strike water temperature is calculated

When strike water meets the grain, the heat the water loses equals the heat the grain gains. Grain holds about 40% as much heat as the same weight of water, which gives John Palmer’s strike water equation:

T_w = \frac{0.4}{R}\,(T_2 - T_1) + T_2

where $T_w$ is the strike water temperature, $T_1$ the grain temperature, $T_2$ the target mash temperature and $R$ the ratio of water to grain by weight. The calculator takes the ratio by volume, in L/kg or qt/lb, and turns it into a weight ratio with the density of hot water, 0.985 kg/L.

For example, 4.5 kg of grain at 20 °C, mashed at 3 L/kg to rest at 66 °C, needs 13.5 L of strike water at 72.2 °C. In US units, a mash at 1.5 qt/lb with grain at 68 °F that should rest at 152 °F needs strike water at about 163 °F.

The equation assumes the tun does not take any heat. Preheat it, or measure its heat capacity once and include it.

Inside Foambyte, mash and boil profiles keep your mash steps and water-to-grain ratio, so every recipe starts from the way you brew.

Reference tables

Strike water temperature (°C) by target mash temperature (rows) and water-to-grain ratio (columns), grain at 20 °C, preheated tun
Mash \ ratio	2.5 L/kg	3.0 L/kg	3.5 L/kg	4.0 L/kg
62 °C	68.8	67.7	66.9	66.3
64 °C	71.1	70.0	69.1	68.5
65 °C	72.3	71.1	70.2	69.6
66 °C	73.5	72.2	71.3	70.7
67 °C	74.6	73.4	72.5	71.8
68 °C	75.8	74.5	73.6	72.9
70 °C	78.1	76.8	75.8	75.1

Strike water temperature (°F) by target mash temperature (rows) and water-to-grain ratio (columns), grain at 68 °F, preheated tun
Mash \ ratio	1.25 qt/lb	1.50 qt/lb	1.75 qt/lb	2.00 qt/lb
144 °F	156	154	152	151
148 °F	160	158	157	156
150 °F	163	161	159	158
152 °F	165	163	161	160
154 °F	167	165	164	162
156 °F	170	167	166	165
158 °F	172	170	168	167

Sources

John J. Palmer. How to Brew, Brewers Publications, 2006. Strike water and infusion equations, with grain at 40% of the heat capacity of water and hot water at 0.985 kg/L (chapter 16, Infusion Calculations, updated 2025); 3rd edition, online version with the author's updates.

Frequently asked questions

What is strike water?

Strike water is the hot water you mix with the crushed grain to start the mash. The grain is cooler than the mash should be, so the water has to be hotter than the target mash temperature to make up the difference.

Why did my mash come out colder than planned?

Usually because the mash tun absorbed heat. The calculation assumes a preheated tun. Warm it with hot water before mashing in, or measure your tun once with the mash tun calibration calculator and include it. Stirring well before you read the temperature also matters: a mash has hot and cold pockets at first.

What water-to-grain ratio should I use?

Many brewers mash at about 2.5 to 4 L/kg (1.25 to 2 qt/lb). A thinner mash is easier to stir and holds its temperature better; a thicker mash leaves room for later infusions in a step mash.

Does the grain temperature matter?

Yes. Grain stored in a cold garage or a warm attic changes the strike temperature by a few degrees. Measure it, or use the room temperature if the grain has been indoors.

Is it safer to aim a little hot?

Many brewers heat the water a degree or two above the result and let it cool in the tun while they stir, because cooling a mash with a little cold water is easier than heating it. Check the temperature after mixing and adjust before the rest starts.