How do I calculate mash tun volume?

Add together the mash water volume, the grain displacement volume (about 0.67L per kg of grain), and any dead space below the false bottom. Add 10% headspace on top.

What water-to-grain ratio should I use?

A typical mash ratio is 2.5-3.0 litres per kg for most beers. Thicker mashes (2.0-2.5 L/kg) favour body and sweetness. Thinner mashes (3.0-4.0 L/kg) favour fermentability and dryness.

What is mash tun dead space?

Dead space is the volume below the false bottom or manifold that cannot be drained. It typically ranges from 0.5-2L depending on your mash tun design. Measure yours by adding water and draining.

How much volume does grain displace?

Crushed grain displaces approximately 0.67 litres per kilogram. This varies slightly with crush size and grain type but 0.67L/kg is a reliable average for calculations.

Can I convert a cooler into a mash tun?

Yes, cooler mash tuns are very popular in homebrewing. They provide excellent insulation for maintaining mash temperature. Add a stainless steel braided hose or false bottom for lautering. A 38-48L cooler handles most 23L batches comfortably.

BrewCalcs

Mash Tun Calculator — Brewing Equipment

Calculate mash tun volume needed for your grain bill and water ratio.

Grain Weight

Total grain bill weight

Water-to-Grain Ratio

Litres of water per kg grain

Grain Absorption Rate

Water absorbed per kg (typically ~1.0)

Dead Space

Volume below false bottom

How We Calculate This

Mash Tun Volume Calculation

The total mash volume is: Mash Water + Grain Displacement + Dead Space. Mash water = grain weight x water ratio. Grain displacement = grain weight x 0.67 L/kg. An additional 10% headspace is added for stirring and thermal expansion.

Choosing the Right Ratio

Thicker mashes (lower L/kg ratio) promote enzyme concentration and can produce more body. Thinner mashes allow easier lautering and more complete conversion. Most brewers find 2.5-3.0 L/kg a good compromise.

Frequently Asked Questions

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Last updated: February 2026

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