Mash Size

BrewCo Brew Tools

Use this free mash size calculator to check your mash tun is big enough before brew day — working out the total volume of water and grain combined.

How to use it

  1. Weigh your total grain bill.
  2. Decide your mash thickness — typically 2.5–3.5 L per kg of grain.
  3. Read off the total mash volume, and check it against your tun's capacity.
Typical range: 2.5–3.5 L/kg. Grain itself takes up roughly 0.67L per kg of space.
— L
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Why does mash tun size matter?

If your grain and water combined don't fit your tun with enough headspace for stirring, you'll struggle to mash properly — and risk boiling over or spilling. Checking this before brew day, especially for bigger or higher-gravity batches, saves a stressful surprise partway through your mash.

More free home brew calculators

Browse our range of mash tuns and all-grain brewing gear at BrewCo UK, Sowerby Bridge.