What is a standard homebrew batch size?

The most common homebrew batch sizes in the UK are 23L (standard kit size), 19L (Corny keg), and smaller 10-12L stovetop batches. Commercial pilot systems often brew 50-100L.

Why do I always end up with less beer than planned?

Unmeasured losses add up: grain absorption, boil-off, trub left in the kettle, yeast cake in the fermenter, and transfer losses. Measuring each loss individually lets you plan accurately.

How do I reduce losses?

Use hop bags to reduce trub, keep grain crush consistent, tilt vessels toward drains, use conical fermenters, and minimise transfer steps. Even small improvements add up to more beer in the glass.

How do I calculate grain absorption?

Grain absorbs approximately 0.8-1.1 litres of water per kilogram. The default of 1.0 L/kg is a good starting point. Fine-crushed grain absorbs slightly more. Measure your actual absorption over a few brews and adjust this value to match your system.

Should I account for trub loss in my batch size?

Yes, always. Trub (yeast sediment, hop debris) typically accounts for 1-2L of loss in a 23L batch. Plan your pre-boil volume to ensure you have enough wort after all losses to fill your fermenter to the desired level.

BrewCalcs

Batch Size Calculator — Recipe Design

Calculate final batch size accounting for all system losses.

Target Final Volume

Beer into keg/bottles

Boil-Off Rate

Boil Time

Kettle Trub Loss

Fermenter Loss

Yeast cake and trub

Transfer Loss

Include Grain Absorption

Add water lost to grain

Grain Weight

Absorption Rate

How We Calculate This

Working Backwards from Target Volume

Total Water = Target Volume + Boil-Off + Trub Loss + Grain Absorption. This ensures you start with enough water to end up with your desired final volume after all losses.

Loss Categories

Boil-off is evaporation during the boil. Trub loss is wort left behind with hop and protein sediment. Grain absorption is water retained by the grain (typically ~1L/kg). Transfer and fermenter losses cover everything else.

Frequently Asked Questions

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Calculate expected pre-boil gravity from post-boil targets.

Post-Boil Volume Calculator

Calculate post-boil volume from pre-boil volume and boil-off rate.

Last updated: February 2026

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