# How hot should my strike water be?

Works out the strike water temperature and volume for an all-grain mash from the grain weight, the water-to-grain ratio, the grain temperature and the target mash temperature (Palmer’s infusion equation).

- Page: https://www.acalculator.org/food/strike-water-calculator
- JSON spec: https://www.acalculator.org/food/strike-water-calculator.json
- Version: 806b4cabdb10

## Default answer

Example with the default inputs (Units US, Grain weight (lb) 10, Water to grain (qt/lb) 1.25, Grain temperature (°F) 68, Target mash temperature (°F) 152): Heat the strike water to 165.4 degrees (°F with US units, °C with metric).

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| units | Units | US (pounds, quarts, °F) or metric (kilograms, liters, °C). |
| g | Grain weight (lb) | The weight of the grain bill, in pounds. |
| r | Water to grain (qt/lb) | Quarts of strike water per pound of grain. |
| t1 | Grain temperature (°F) | The temperature of the grain, often room temperature. |
| t2 | Target mash temperature (°F) | The mash temperature you want. |
| gkg | Grain weight (kg) | The weight of the grain bill, in kilograms. |
| rl | Water to grain (L/kg) | Liters of strike water per kilogram of grain. |
| t1c | Grain temperature (°C) | The temperature of the grain, often room temperature. |
| t2c | Target mash temperature (°C) | The mash temperature you want. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| strike | Strike water temperature | Tw = (c ÷ r)(T2 − T1) + T2, in °F (US) or °C (metric). |
| volume | Strike water volume | Ratio × grain weight, in quarts (US) or liters (metric). |
| gallons | Strike water (US gallons) | The volume in US gallons (4 quarts), for the US units. |

## Method

Tw = (c ÷ r)(T2 − T1) + T2, c = 0.2 with qt/lb and °F or 0.41 with L/kg and °C; volume = r × grain weight.

## Assumptions

- The mash tun is preheated, so it takes no heat from the water; a cold tun needs hotter water.
- 0.2 and 0.41 are the grain’s heat capacity relative to water in each set of units; the two systems can differ by a few tenths of a degree.
- All the strike water goes in at once (a single infusion).

## Worked examples

1. units = us, g = 10, r = 1.25, t1 = 68, t2 = 152 gives strike = 165.4, volume = 12.5, gallons = 3.13. Source: John Palmer, How to Brew, online edition, Calculating Strike Water Temperature (Tw = (0.2 ÷ r)(T2 − T1) + T2; r in qt/lb, °F), http://howtobrew.com/book/section-3/how-the-mash-works/calculating-strike-water-temperature.
2. units = metric, gkg = 5, rl = 2.5, t1c = 18, t2c = 67 gives strike = 75, volume = 12.5. Source: Home Brew Answers, Calculating Strike Water Temperature For Mashing (Tw = (0.41 ÷ R)(T2 − T1) + T2 with L/kg and °C; example (0.41 ÷ 2.5) × (67 − 18) + 67 = 75 °C), https://homebrewanswers.com/document/calculating-strike-water-temperature-for-mashing/ (shown there as 75 °C).
3. units = us, g = 12, r = 1.5, t1 = 60, t2 = 154 gives strike = 166.5, volume = 18, gallons = 4.5. Source: John Palmer, How to Brew, online edition, Calculating Strike Water Temperature (Tw = (0.2 ÷ r)(T2 − T1) + T2; r in qt/lb, °F), http://howtobrew.com/book/section-3/how-the-mash-works/calculating-strike-water-temperature.

## FAQ

### How do I calculate strike water temperature?

With Palmer’s initial infusion equation: Tw = (0.2 ÷ r)(T2 − T1) + T2, where r is quarts of water per pound of grain, T1 the grain temperature and T2 the target mash temperature in °F. For 1.25 qt/lb, grain at 68 °F and a 152 °F mash: 0.16 × 84 + 152 = 165.4 °F.

### What is the metric version?

Tw = (0.41 ÷ r)(T2 − T1) + T2 with r in liters per kilogram and temperatures in °C. For 2.5 L/kg, grain at 18 °C and a 67 °C mash: 0.164 × 49 + 67 = 75.0 °C.

### Why is the strike water hotter than the mash?

The grain is colder than the mash, so it takes heat from the water when you mix them. The water must start hotter by the amount the grain will absorb, which depends on how much water there is per pound or kilogram of grain.

### What water-to-grain ratio should I use?

Many brewers use 1 to 2 quarts per pound (about 2 to 4 L/kg). A thicker mash (less water) needs hotter strike water for the same mash temperature, because less water carries the heat.

### Why did my mash come out cooler than planned?

The equation assumes the mash tun is already warm. A cold tun absorbs heat too, so preheat it with hot water, or heat the strike water a few degrees more and let it cool to the target before adding the grain.

## Sources

- John Palmer, How to Brew, online edition, Calculating Strike Water Temperature (initial infusion equation Tw = (0.2 ÷ r)(T2 − T1) + T2; r in quarts per pound, temperatures in °F). http://howtobrew.com/book/section-3/how-the-mash-works/calculating-strike-water-temperature (the site’s security certificate had expired when checked on 2026-10-19; the equation matches the Home Brew Answers page below)
- Home Brew Answers, Calculating Strike Water Temperature For Mashing (metric form Tw = (0.41 ÷ R)(T2 − T1) + T2 with R in L/kg and °C; example (0.41 ÷ 2.5) × (67 − 18) + 67 = 75 °C). https://homebrewanswers.com/document/calculating-strike-water-temperature-for-mashing/ (retrieved 2026-10-19)