Strike water calculator
Enter your target mash temperature, grain temperature, grain weight and either a water-to-grain ratio or a water volume. You get the temperature and the amount of strike water, with an optional correction for a cold mash tun. Works in °F and °C, qt/lb and L/kg.
Mash
Usually room temperature. Measure it if the grain was stored somewhere cold.
Strike water as
Mash tun with sparge: 1.2–1.7 qt/lb. Full-volume BIAB: 1.9–2.9 qt/lb.
Heat strike water to
162.7 °F
- Target mash
- 152.0 °F
- Strike water
- 4.12 gal · 1.50 qt/lb
- To warm the grain
- +10.7 °F
- To warm the mash tun
- none
- Strike temperature in °C
- 72.6 °C
Runs in your browser. Nothing you enter is sent or stored.
Why strike water has to be hotter than the mash
When you dough in, the hot water and the cooler grain trade heat until they meet at one temperature. The grain warms up, the water cools down. To land on your mash temperature, the water has to start above it.
How much above depends on the thermal mass of the grain. Per kilogram, malt takes about 0.4 times the heat that water does to warm by one degree. The calculator uses Palmer’s infusion equation from How to Brew with that factor: the bigger the gap between grain and mash temperature, and the less water per kilogram of grain, the hotter the strike water has to be.
T_strike = T_mash + 0.4 / R × (T_mash − T_grain)
- T_mash
- Target mash temperature
- T_grain
- Grain temperature before dough-in
- R
- Water-to-grain ratio in L/kg
- 0.4
- Heat capacity of grain relative to water
Temperatures in °F and ratios in qt/lb are converted first. This is the case for mashing in the kettle or a preheated tun. For a cold tun, see below.
| Water-to-grain ratio | Strike water |
|---|---|
| 1.2 qt/lb (2.5 L/kg) | 166 °F (74.5 °C) |
| 1.44 qt/lb (3 L/kg) | 164 °F (73.3 °C) |
| 1.68 qt/lb (3.5 L/kg) | 162 °F (72.4 °C) |
| 1.92 qt/lb (4 L/kg) | 161 °F (71.7 °C) |
| 2.4 qt/lb (5 L/kg) | 159 °F (70.8 °C) |
| 2.88 qt/lb (6 L/kg) | 158 °F (70.1 °C) |
Water-to-grain ratio: L/kg and qt/lb
The water-to-grain ratio, also called mash thickness, is the strike water volume divided by the grain weight. US recipes give it in quarts per pound, metric recipes in liters per kilogram. 1 qt/lb is about 2.08 L/kg.
A thick mash has less water to carry heat, so it needs hotter strike water. A thin mash, as in full-volume BIAB, needs only a few degrees extra. Enter your grain weight and either the ratio or the water volume: the calculator works out the other and always shows how much water to heat.
R = V / m
1 qt/lb = 2.084 L/kg
- V
- Strike water volume in liters
- m
- Total grain weight in kilograms
| Setup | L/kg | qt/lb |
|---|---|---|
| Mash tun with sparge | 2.5–3.5 | 1.2–1.7 |
| Step mash by infusion (first rest) | 2–3 | 1.0–1.4 |
| BIAB, full volume, no sparge | 4–6 | 1.9–2.9 |
Mash tun heat loss and preheating
The basic formula only accounts for the grain. Whether you need more depends on where you mash.
Mash in the kettle or a preheated tun: no correction. In BIAB or an all-in-one system you heat the water in the vessel you mash in, so the metal is already at strike temperature. The same goes for a tun you preheated. This is the calculator’s default.
Cold mash tun: a cooler or a separate tun at room temperature soaks up heat, so the strike water has to warm the tun too. How much depends on the tun’s thermal mass, its weight times its specific heat relative to water, and on how much strike water shares the job. A 4 kg (9 lb) plastic cooler is worth about 1.2 L (0.3 gal) of water. Spread over 15 L (4 gal) of strike water, it adds about 3.8 °C (7 °F). Choose “Cold mash tun” in the calculator, pick the material and enter the empty weight; the result shows the correction separately.
- Preheat a cooler mash tun with a few liters of hot water for 10–15 minutes, then drain it and add your strike water. Then keep the default “Mash in the kettle / preheated tun”.
- Or pour the strike water in a few degrees hotter than calculated, close the lid and wait until it has dropped to the strike temperature before you add the grain.
- Mashing in the kettle, as with BIAB or an all-in-one system? The kettle is already hot from heating the water, so no extra correction is needed.
- Not preheating? Choose “Cold mash tun”: stainless steel counts 0.12, aluminum 0.22 and an insulated plastic cooler about 0.3 of its weight as water.
- Heat lost to the room while you dough in is not part of any formula. Expect a brew or two to dial in your setup, or measure your tun with the calibration in a BrewForge equipment profile and enter it as “Known thermal mass”.
T_strike = T_mash + 0.4 / R × (T_mash − T_grain) + M / W × (T_mash − T_tun)
- M
- Mash tun thermal mass: weight × specific heat (liters of water equivalent)
- W
- Strike water volume
- T_tun
- Mash tun temperature before dough-in (usually the grain temperature)
Specific heat relative to water: stainless steel 0.12, aluminum 0.22, insulated plastic cooler ≈ 0.3 (the value BeerSmith suggests; mostly the inner wall takes up heat). A 6 kg stainless tun ≈ 0.7 L, a 4 kg cooler ≈ 1.2 L.
Hitting your mash temperature on brew day
The calculator gets you close. Good habits at dough-in get you the rest of the way, and a few notes from each brew day make the next one more accurate.
- Measure the grain temperature instead of guessing. Grain stored in a cold garage can be 10 °C (18 °F) below room temperature.
- Stir thoroughly while you add the grain and break up every dough ball.
- Wait a few minutes, then check the temperature in several spots of the mash.
- Too cold: stir in a little boiling water. Too hot: stir with the lid open or add some cold water.
- Note how far you missed. If you always land a degree low, raise the target mash temperature in the calculator by that amount.
Built into every BrewForge recipe
In BrewForge your equipment profile stores your water-to-grain ratio and grain temperature. Each recipe uses its first mash step as the target, works out the strike water volume from the grain bill and the strike temperature from that, and shows both in the recipe, on brew day and on the printable brew day sheet.
- Strike volume and temperature from your grain bill and equipment profile
- Mash tun capacity and mash water limits taken into account
- Shown on brew day and the printable brew day sheet
Use this calculator via API
The same calculation is also a free JSON API: no account, no key, one GET request. Handy for scripts, spreadsheets and AI assistants that should use exact brewing math instead of estimating it.
Add units=imperial (or one unit parameter per value) for °F, gallons and pounds. Every answer lists the inputs, the units and the formula it used.
GET https://brewforge.sh/api/public/calc/strike-water?mashTemp=67&grainWeight=5&ratio=3
FAQ
Questions & answers
What temperature should my strike water be?
Usually 3–10 °C (5–18 °F) above your target mash temperature, depending on how thick your mash is and how cold the grain is. For a 67 °C (153 °F) mash at 3 L/kg (1.44 qt/lb) with grain at 20 °C (68 °F), heat the water to about 73 °C (164 °F).
What is a good water-to-grain ratio?
For a classic mash tun with sparge, 2.5–3.5 L/kg (1.2–1.7 qt/lb) is common, with 3 L/kg (1.44 qt/lb) a good starting point. Full-volume BIAB uses all the water in the mash, so it typically runs at 4–6 L/kg (1.9–2.9 qt/lb).
Why is my mash temperature lower than calculated?
Most often the mash tun was cold and not accounted for, the grain was colder than you entered, or the thermometer reads off. Stir in a little boiling water to correct it. Next time preheat the tun or choose “Cold mash tun” in the calculator, and measure the grain temperature.
Do I need to preheat my mash tun?
For a cooler or a separate mash tun, either preheat it or choose “Cold mash tun” in the calculator and enter its material and weight, so the strike water is hot enough to warm the tun too. If you mash in the kettle you heated the water in, it is already hot and needs no correction.
What if I don’t know my mash tun’s thermal mass?
You rarely need the exact number. Mashing in the kettle or a preheated tun needs no correction at all. For a cold tun, its empty weight and material give a good estimate: weight × 0.12 for stainless steel, 0.22 for aluminum, about 0.3 for a plastic cooler. Note how far you miss on brew day and adjust, or measure the tun once with the calibration in a BrewForge equipment profile.
Does the strike water calculator work for BIAB?
Yes. Keep “Mash in the kettle / preheated tun”, enter your grain weight and switch the water to Volume for your full water volume. Because BIAB mashes are thin, the strike water only needs to be a few degrees above the mash temperature.
Can I use it for a step mash?
Use it for the first rest. For each following rest you add boiling water or pull a decoction, and the step mash calculator works out how much.
Do the math once. BrewForge does it every brew.
Recipes, brew day and fermentation in one place, with these calculations built in. Free for up to 20 brews.