What is the ideal sparge water temperature?

Most brewers target 168–170 °F (76–77 °C) at the grain bed. The actual water you add must be slightly hotter to compensate for heat lost to the grain and tun. This calculator estimates the needed infusion temperature based on your grain and ambient temperatures.

How much water does grain absorb?

A common rule of thumb is 0.1–0.125 gal/lb (0.83–1.04 L/kg). This calculator uses 0.12 gal/lb (1.0 L/kg) by default — adjust it if your system absorbs more or less.

What is system deadspace?

Deadspace is wort that remains trapped in the mash tun, tubing, or pump after draining — it never reaches the kettle. Accounting for it prevents coming up short on pre-boil volume. Typical values are 0.25–0.5 gal (1–2 L) for most homebrew setups.

Does this work for batch sparge and fly sparge?

Yes. The sparge volume math is the same for both methods — the difference is in how you apply the water. For batch sparge, pour all the sparge water at once. For fly sparge, run it continuously while draining, maintaining the same level. Both aim to collect the same pre-boil volume.

Why might my actual volume differ from the calculated result?

Grain absorption varies by crush, malt type, and mash temperature. Deadspace varies by equipment. Boil-off depends on kettle diameter, lid use, and burner intensity. These are estimates — measure your actual system losses over a few batches to dial in the constants.

Sparge Water Calculator

Enter your grain bill, mash ratio, pre-boil target, absorption, and deadspace to estimate sparge water volume and temperature for all-grain homebrew.

Brew Day Parameters

Unit System

Grain Bill Weight (lb)

Mash Water Ratio (qt/lb)

Typical: 1.0–2.0 qt/lb

Target Pre-boil Volume (gal)

Grain Absorption Rate (gal/lb)

Default: 0.12 gal/lb — adjust for your system

System Deadspace (gal)

Target Mash Temperature (°F)

Used to estimate sparge infusion temperature

Results

Enter values and click Calculate

Summary

This sparge water calculator estimates how much hot water to run over your grain bed after mashing to hit a pre-boil volume target. It accounts for grain absorption and mash-tun deadspace, and calculates an estimated sparge water temperature. Boil-off and post-boil trub/chiller losses are outside this pre-boil calculation. It supports US and metric units.

How it works

Select your unit system: US (gallons / °F) or metric (liters / °C).
Enter your total grain bill weight and mash water ratio (qt/lb or L/kg).
Enter the pre-boil volume you want to collect in the kettle.
Optionally enter system deadspace and adjust the grain absorption rate for your equipment.
Click Calculate to see sparge water volume and recommended sparge temperature.
Adjust values and recalculate until your volumes balance across the brew day.

Use cases

Plan batch sparge water volume before brew day to avoid running short.
Calculate fly sparge volume for a long continuous rinse on a HERMS or RIMS system.
Verify your total water needs (mash + sparge) fit your hot liquor tank capacity.
Find the right sparge temperature to keep the grain bed at 168–170 °F (76–77 °C).
Account for grain absorption and tun deadspace when hitting a pre-boil gravity target.
Cross-check volume math for a new recipe before scaling up.
Quickly recalculate for a partial grain bill when adjusting a recipe mid-session.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu