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Strike Water Temperature Calculator

Enter your ratio, grain temp and target mash temp to find the strike water temperature.

How it is calculated

The tool uses the common brewing formula Tw = (0.41 ÷ R) × (T2 − T1) + T2. R is the water-to-grain ratio in litres of water per kilogram of grain, T1 is the grain temperature and T2 the mash temperature you want, both in °C. The constant 0.41 is the metric form of the 0.2 used with quarts per pound, and it reflects how much less heat the grain holds than the same weight of water. The tool shows the strike temperature in °C and °F (°F = °C × 9/5 + 32) and the rise above the target. The ratio must be above zero; temperatures may be any value. A thinner mash (higher R) needs less extra heat, and a colder grain needs more. The formula ignores heat taken up by the mash tun, so equipment may need a small extra allowance.

Worked example

You mash at 2.6 L of water per kg of grain, the grain is at 20 °C, and you want a 67 °C mash. Step 1: the temperature difference is 67 − 20 = 47. Step 2: the factor is 0.41 ÷ 2.6 = 0.1577. Step 3: 0.1577 × 47 = 7.4, the rise above target, and adding the 67 gives a strike water temperature of 74.4 °C. That equals 165.9 °F, so the water has to be heated 7.4 °C hotter than the mash goal.

Try this example →

Common mistakes

  • Entering the ratio in quarts per pound. This tool expects litres per kilogram, so 1.25 qt/lb must be entered as about 2.6 L/kg. Using 1.25 would give a far too hot strike water.
  • Using the target mash temperature as the strike temperature. The water must be hotter than the target, because cold grain pulls the mixture down; here by 7.4 °C.
  • Typing the temperatures in °F. The fields are in °C; the °F figure is only an output.
  • Entering the room temperature when the grain was stored somewhere colder, such as a garage in winter. The grain temperature is the temperature of the grain itself.
  • Forgetting to preheat the mash tun. The formula does not include the heat the vessel takes, so a cold metal tun can leave the mash a few degrees below target.

About this calculator

All-grain brewers heat "strike water" hotter than the target mash temperature because mixing it with room-temperature grain pulls the combined temperature down. The standard homebrewing formula in metric units is: strike temp = (0.41 ÷ R) × (target mash temp − grain temp) + target mash temp, where R is the water-to-grain ratio in litres per kilogram and temperatures are in °C (the constant 0.2 applies only when R is in quarts per pound and temperatures are in °F) — the constant reflects the specific heat ratio between water and grain.

Homebrewers use this every brew day to hit their mash temperature on the first try instead of scrambling to add boiling or ice water mid-mash, and professional brewmasters rely on the same relationship when scaling recipes to different mash tun sizes and grain bills, since hitting the right mash temp directly controls the fermentability and body of the finished beer.

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  • Editorial team

    If your recipe lists the ratio in quarts per pound, multiply by about 2.09 to get litres per kilogram before typing it in, since this tool expects litres per kilogram. Treat the result as the water temperature to aim for when dough-in begins, and check the mash with a thermometer a few minutes later. Preheating the vessel is a separate step this tool does not model. Does your mash tun lose a lot of heat? Tell us how much you add.

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