Mash Strike Water Temperature Calculator

When you pour hot water onto cold grain, the temperature drops. How much it drops depends on how much water you are adding relative to the grain, and how cold the grain started. Getting this calculation wrong means starting your mash too hot (enzymes denature above 168°F) or too cold (conversion is sluggish below 146°F).

The formula comes from John Palmer’s book How to Brew and is the industry standard for homebrewers:

strike_temp = (0.2 / R) × (target_mash_temp - grain_temp) + target_mash_temp

Where R is the mash thickness in quarts of water per pound of grain.

The constant 0.2 is the specific heat of malt relative to water — essentially, grain absorbs about one-fifth as much heat energy per pound as the same volume of water.

Example: mashing at 154°F, with a 1.25 qt/lb ratio, grain at 65°F: strike_temp = (0.2 / 1.25) × (154 - 65) + 154 = 0.16 × 89 + 154 = 14.24 + 154 = 168.24°F

So heat the strike water to about 168°F before adding it to the grain.

Common mash thickness ratios:

• Thin mash (1.5 qt/lb): easier to stir, slightly better conversion efficiency, more dilute wort
• Medium mash (1.25 qt/lb): the most common for most styles
• Thick mash (1.0 qt/lb): better for body and mouthfeel, harder to stir, slightly lower efficiency

The malt temperature matters. Grain stored in a cold garage in winter can be 50°F — that adds several degrees to the required strike temperature versus room-temperature grain.

After the first few batches with a given setup, note whether your actual mash temperature runs slightly high or low versus the formula and adjust accordingly — every system has its own thermal characteristics.