What Is a Mash Tun? All-Grain Brewing Equipment Explained

What Is a Mash Tun?

A mash tun is the vessel where crushed grain is steeped in hot water — the mash — to convert starches into fermentable sugars before the resulting wort is drained off and boiled. It's the defining piece of equipment that separates all-grain brewing from extract or kit brewing, where that conversion has already been done for you at the maltings.

Traditionally, a mash tun is one of three separate vessels in an all-grain setup: a hot liquor tank (HLT) for heating water, the mash tun itself for conversion and lautering, and a boil kettle. Each has its own plumbing, and the brewer manually transfers liquid between them at each stage.

Do You Need a Separate Mash Tun?

Not necessarily — and for most home brewers moving from kits to all-grain, you don't want one. A traditional three-vessel mash tun setup takes up significant space, needs dedicated plumbing between vessels, and represents a real jump in both cost and complexity. Two more practical routes get you the same conversion without any of that:

• Brew in a Bag (BIAB) — mash and boil in a single pot using a fine nylon straining bag or a purpose-made Brew In A Bag setup to hold the grain, then simply lift the bag out to separate wort from spent grain. No second vessel, no plumbing, no separate lautering step.
• An all-in-one system like the Grainfather G30v3, G40, or G70 — these combine mash, sparge, and boil into a single electric vessel with a built-in recirculation pump and perforated basket, giving you the control and repeatability of a traditional three-vessel setup without the footprint.

BIAB vs a Traditional Mash Tun

The trade-off is mostly about efficiency and batch size. A dedicated mash tun with proper lautering typically extracts slightly more sugar from your grain than BIAB, and traditional multi-vessel setups scale more easily to larger batches. BIAB and all-in-one systems close most of that gap in practice — a well-executed BIAB mash with a good crush and adequate water-to-grain ratio gets you very close to three-vessel efficiency, and an all-in-one system like the Grainfather typically matches it outright thanks to its recirculation.

For the vast majority of home brewers making 20–25 litre batches, the space and cost saved by skipping a dedicated mash tun far outweighs the small efficiency difference.

Mash Temperature and Process

Whichever method you use, the mashing principles are the same:

• Most single-infusion mashes sit at 65–68°C for 60 minutes — lower temperatures favour a more fermentable, drier wort; higher temperatures favour body and residual sweetness
• Maintain a consistent temperature throughout — this is where all-in-one electric systems have a real edge over a passive cooler-box mash tun, since they actively hold temperature rather than relying on insulation alone
• Use our Mash Size calculator to work out your grain and water volumes, and our Strike Temperature calculator to hit your target mash temperature accurately

Getting Started With All-Grain Brewing

If you're moving from kit brewing to all-grain for the first time, BIAB with a simple straining bag and your existing brew pot is the lowest-cost way to try it before committing to dedicated equipment. Browse our all-grain brewing collection for crushed malts, all-grain recipe kits, and the Grainfather range if you're ready to step up to a dedicated all-in-one system.