Sparging is rinsing the grain bed with hot water to extract remaining sugars after the mash. Fly sparging slowly sprinkles water over the grain bed while draining from below. Batch sparging adds all the water, stirs, settles, then drains. Both achieve good efficiency.

What temperature should sparge water be?

Heat sparge water to 76-78 degrees C. This temperature helps rinse sugars efficiently without extracting harsh tannins from the grain husks. Do not exceed 80 degrees C at the grain bed as tannin extraction increases sharply.

How much water do grains absorb?

Grains typically absorb 0.8-1.1 litres per kilogram, depending on how well you drain and whether you squeeze the grain bag. BIAB (brew in a bag) brewers lose less as they can squeeze. Traditional mash tuns lose more to dead space.

What is a good boil-off rate?

Most homebrew kettles boil off 3.5-4.5 litres per hour with a vigorous boil. Electric kettles tend to be at the lower end. Gas kettles can be higher. Measure your own system by noting volume before and after a 60-minute boil.

BrewCalcs

Sparge Volume Calculator

Calculate sparge water volume based on grain absorption, mash volume and target pre-boil volume.

Target Batch Size

Final volume into fermenter

Grain Weight

Total grain bill weight

Water-to-Grain Ratio

Litres of mash water per kg of grain

Boil Time

Duration of the boil

Sparge MethodYour sparging technique

How We Calculate This

Water Calculation

Mash water = Grain weight x Water-to-grain ratio

Pre-boil target = Batch size + Boil-off + Trub loss

Sparge water = Pre-boil target - (Mash water - Grain absorption - Dead space)

Total water = Mash water + Sparge water

Frequently Asked Questions

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Last updated: March 2026

All calculations are estimates. Always verify values and adjust based on your equipment and ingredients.