Brew in a bag, the easiest all-grain method

The idea in one paragraph

You put your whole crushed grain bill inside a large, fine-mesh bag, submerge it in your full batch volume of hot water in a single pot, mash as usual, then lift the bag straight out. There is no separate sparge, no lautering, and often no second vessel at all.

Because the bag holds the grain and the same pot goes on to the boil, brew in a bag needs only one big pot and one bag beyond what an extract brewer already owns. It is the cheapest and simplest way into real all-grain brewing that we teach.

Because the same pot holds the mash and then goes straight on to boil, BIAB also saves a step that traditional three-vessel setups cannot skip: transferring hot wort between a mash tun and a separate boil kettle, with the heat loss and spillage risk that transfer carries. Everything happens in one place, which is a large part of why the method suits smaller kitchens and balconies.

Sizing your pot and your burner

Because you mash in your full batch volume rather than a smaller, concentrated mash, you need a pot large enough to hold your whole boil volume plus the grain, with headroom to spare for the boil. For a typical 19 to 23 litre batch that usually means a 30 to 35 litre pot.

Heating that much water to mash and then boil temperature takes a serious burner. A standard kitchen hob under-delivers for anything past small test batches, which is why most BIAB brewers in India move outdoors to an LPG burner once they are brewing regularly.

Water absorption by the grain also matters more in BIAB than in a sparged system, since there is no second rinse to recover sugar left behind. Recipe calculators built for BIAB account for this by specifying a slightly larger total water volume up front, and it is worth using one rather than estimating water volumes by eye on your first few attempts.

Lifting the bag without a mess

A soaked grain bag holding 4 to 6 kilograms of wet malt is heavy, and lifting it out badly is the method's main failure point. A pulley rigged over the pot, or a second pair of hands, turns a precarious lift into a non-event. Let the bag drain over the pot for ten to fifteen minutes rather than squeezing it hard, since aggressive squeezing pushes tannins out of the grain husk and can leave the beer tasting astringent.

A large stock pot lid propped over the draining bag, or a purpose-built stand that suspends the bag directly over the empty kettle, both solve the same problem: giving the wort somewhere clean to drip into while the bag itself sits well clear of the floor or countertop.

Mash temperature still matters

Nothing about the single-pot method changes the chemistry. You are still converting starch to sugar in the same 63 to 70 °C window, and the same trade-off between fermentability and body still applies, covered fully in our mash temperature guide. Because you are mashing in a full volume of water rather than a thick, concentrated mash, BIAB tends to run slightly less efficient at pulling sugar out of the grain, so many BIAB recipes call for a little extra grain to compensate.

Where BIAB brewers go next

Once you are comfortable with the single-pot method, the step up to a dedicated mash tun and separate boil kettle is mostly about batch size and convenience rather than beer quality. Plenty of serious homebrewers stay on BIAB permanently because it is simple, cheap and produces genuinely good beer. If your next question is what to do with the wort once the bag comes out, our guide on chilling wort fast covers the step right after the boil.

Batch size is the other practical ceiling on a single-pot method: most home stoves and even outdoor burners struggle to heat and boil much beyond about 25 litres of water in a single pot within a reasonable time, which caps typical BIAB batches at a finished volume somewhere around 19 to 23 litres unless you invest in serious outdoor brewing equipment.