What is the strike water formula?

Strike temp = (0.2 ÷ R) × (target − grain) + target, where R is the water-to-grist ratio in quarts per pound and 0.2 is the ratio of grain to water specific heat. It accounts for the grain absorbing heat and cooling the water down to the target.

Why 0.2 in the formula?

0.2 is the approximate specific heat of grain relative to water (water = 1.0). Grain only absorbs about a fifth as much heat per degree as water, so the formula weights the grain's cooling effect by that factor divided by the water ratio.

Does this account for my mash tun losing heat?

No — it assumes a preheated, insulated tun. A cold tun absorbs heat and drops your mash temp. Preheat the tun with hot water first, or add 2 to 4 °F to the strike temp to compensate for a cold cooler.

What units does it support?

You can switch between Fahrenheit and Celsius. The underlying ratio (0.2) is dimensionless, so the same formula works in either scale as long as all temperatures use the same unit.

My mash came in too low — what happened?

Common causes are a cold mash tun stealing heat, cold grain you did not account for, or stirring in cold spots. Preheat the tun, stir thoroughly, and if it is still low add small amounts of boiling water and recalculate, or apply direct heat if your tun allows.

Strike Water Temperature Calculator

This calculator tells you exactly how hot your strike (infusion) water must be so that when it hits the grain, the mash settles at your target temperature. No more guessing and chasing the thermometer after dough-in.

How it works

When hot water meets cool grain, the two reach an equilibrium temperature. Grain has a specific heat of about 0.4 BTU/lb·°F versus water at 1.0 — roughly a 0.2 ratio when the grain absorption coefficient is folded in. The standard single-infusion strike formula is:

strike_temp = (0.2 / R) × (target − grain_temp) + target

Where:

R is the water-to-grist ratio in quarts per pound.
target is your desired mash temperature.
grain_temp is the temperature of the dry grain.
0.2 is the grain-to-water specific-heat ratio.

The thinner the mash (higher R), the closer the strike temp is to the target, because there is more thermal mass of water to dominate. A thicker mash (lower R) needs hotter water because the cool grain pulls the equilibrium down more.

Worked example

Mash 10 lb of grain at 68 °F to a target of 152 °F, using 1.25 qt/lb:

strike = (0.2 / 1.25) × (152 − 68) + 152
       = 0.16 × 84 + 152
       = 13.44 + 152
       ≈ 165.4 °F

So heat your strike water to about 165 °F. Pour it over the grain, stir thoroughly, and the mash should stabilize near 152 °F.

Tips and notes

Preheat your mash tun. This formula assumes an insulated, preheated vessel. A cold cooler can steal 2–6 °F. Rinse the tun with hot water first, or add a few degrees to the strike temp.
Use real grain temperature. Grain stored in a cold garage is much colder than room temperature and needs noticeably hotter strike water.
Stir well and measure at multiple points — cold or hot pockets give a misleading single reading. Take the mash temp about a minute after dough-in.
The same formula works in Celsius; just keep every temperature in the same unit (the 0.2 ratio is dimensionless).