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Sparge Water & Brewing Water Volume Calculator

Total brewing water, strike and sparge volumes from batch size, grain weight, boil-off, grain absorption, trub and equipment losses — for batch, fly and no-sparge brewing.

Batch size into the fermenter

Grain weight

Mash water-to-grist ratio

Boil length

Boil-off rate

Grain absorption

Kettle trub + chiller loss

Mash tun dead space

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How it works

Pre-boil = batch + trub + boil-off (× 1.04 hot); strike = grain × ratio; first runnings = strike − absorption − dead space; sparge = pre-boil − first runnings

Water planning works backwards from the fermenter. Add the wort left behind with the trub and what boils off, expand by 4% because hot wort occupies more volume, and you have the pre-boil target. The mash contributes its strike water minus what the grain soaks up (about a litre per kilogram) and what stays in the tun; the sparge makes up the rest. Batch spargers aim for two roughly equal runnings for best efficiency; fly spargers simply run in the sparge volume slowly; brew-in-a-bag brewers put all the water in at the start. Your boil-off rate is the number most worth measuring — it depends on kettle diameter and burner, and ranges from 2 to 6 litres an hour.

Worked example

20 L batch, 5.5 kg grain, 60 min boil at 3.5 L/h, 1.5 L trub: pre-boil 25.0 L (26.0 hot); strike 15.4 L leaves 9.4 L of first runnings, so sparge with 16.6 L — 32.0 L in total.

Frequently asked questions

How do I measure my boil-off rate?

Boil a known volume of water for 30 minutes and measure the loss; double it for the hourly rate. Do it once per kettle and burner.

Why is my batch sparge so much bigger than the first runnings?

A thick mash ratio leaves little first runnings. Either mash thinner (3–3.5 L/kg) or split the sparge into two additions for better efficiency.

Related calculators

Strike Water Temperature Calculator (Mash Infusion)

Temperature to heat your strike water so the mash lands at the target — Palmer’s infusion equation from grain weight, grain temperature and mash thickness (or a total water volume), with mash-tun heat loss as a fixed allowance or worked out from the tun’s weight and material. In °C or °F, kg or lb, litres, quarts or gallons, with mash volume, first runnings, a mash-out infusion and how much hot or cold water fixes a miss.

Boil-Off & Post-Boil Gravity Calculator

Predict post-boil gravity and volume from pre-boil gravity, volume and boil-off rate — or the water to add / extra boil time needed to hit a target OG.

Mash Step Infusion Calculator (Boiling Water Addition)

Volume of boiling water to raise a mash from one rest temperature to the next — protein rest to saccharification, or saccharification to mash-out — from grain weight and current water volume.

This calculator is for educational purposes. Double-check important results before acting on them.