How to Brew in a Bag: The biab method

Learning how to brew in a bag leaves you with a cost-effective way to experience all-grain brewing. High-quality, craft beer is yours with about as much effort as steeping a bag of tea. It’s that easy!

If you want to brew beer at home without much fuss, the brew in a bag (BIAB) method is perfect, and today we’re walking through all the steps. We’ll lay out the equipment you need and provide easy-to-follow instructions so that you can start brewing beer in a bag right away. 

So if you ever wondered how to brew in a bag, read on. It’s easier than you think and far from expensive. Yes, there’s some math and fermentation science involved, but we promise that if you can add a tea bag to a kettle and let it steep, you can brew beer in a bag easily. 

What is the BIAB Method?  

Before we get too far into the instructions, let’s clarify the brew in a bag method. If you want to be technical, this is an all-grain, single-vessel, no sparge method. Let’s break that down, shall we? 

All-Grain means you’ll use water and malted grain to make your wort. In traditional brewing, you probably used malt extract, water, and specialty grains to produce wort. The wort is what you boil and ferment to create beer. 

With all-grain brewing, you soak crushed malted grains in hot water alone. Starch will convert to sugar as the grain soaks, and you’ll have wort ready for fermentation. 

Single-vessel simply refers to whatever boiling pot you plan to use for brewing; no sparge means you can forgo, you guessed it, sparging. 

For the uninitiated, sparging refers to rinsing your mash grains. It maximizes the amount of sugar available but isn’t necessary with the BIAB method. 

Step-By-Step Instructions 

A picture of a dark beer in a pint glass with foam on top. White background.

Now that you have an idea of what an all-grain, single-vessel, no-sparge brewing method means, let’s look at the process in detail. We’ll start by exploring the equipment you’ll need; don’t worry, it isn’t much. 

Then, we’ll cover each of the four unique BIAB steps in detail so you can follow along at home. With this budget-friendly brew method, you’ll be enjoying custom homebrewed beers before you know it. 

Equipment Needed for brewing in a bag

To brew in a bag, you’ll need the following ready to go. You can find most of this on Amazon or a homebrew supply store if you don’t already have it at home. 

Brew Kettle

Though you only need one kettle with the BIAB method, you do need it to be large. The kettle needs to fit your recipe’s pre-volume plus the volume of your wort. Per the Home Brewers Association, a 5 gallon batch of homebrew needs a 10-gallon kettle to accommodate it. 

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Brewer's Edge Mash and Boil
  • Mash up to 16lb of Malt
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Electric kettles made from sturdy and non-reactive stainless steel best. They might cost a little more upfront, but kettles like that last a long time, and you’ll be able to use them for other homebrewing experiments in the future. 

Know that too large of a kettle, one that allows for lots of space above your brew, works against you when it comes to holding temperature. More headspace means your kettle won’t retain heat as efficiently. So, aim for a 10-15 gallon kettle unless you know you’re making extra-large homebrew batches. 

BREw Bag

Brewing in a bag requires a bag; go figure! Technically speaking, you can make your own brew bag if you’re feeling crafty. There are all sorts of tutorials on YouTube and Pinterest to peruse. 

That said, you can purchase a bag as well, and they’re exceptionally affordable. Brew bags are also reusable, so it’s a one-time investment in most cases.  

Look for one that fits the circumference of your brewing kettle easily. The bottom of the bag should not touch the bottom of the kettle, though. If it does, you risk scorching your grain.

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Bellamei Brew Bags Reusable 2 Pack 250 Micron Fine Mesh Bag for Fruit Cider Apple Grape Wine Press Drawstring Straining Brew in a Bag (2 pack-22"×26")
  • Wise Choice: The straining bag is an easy and economical choice for home brewers to start all-grain brewing according to the Brew in a Bag-method. This will eliminates the need for a mash tun, later tun, or hot liquor pot, thus saving your time, space and money.
  • BPA Free & SGS Certified: These brew bags are made of durable nylon mesh and can be washed and reused for multiple times. 250 micron tightly woven and rugged stitching not only make the BIAB durable but also ensure no grains slip into the wort when use.
  • Extra Large Size: 2 extra large brew in a bag size in (26" wide and 22" height), ensure you can brew even the largest of recipes without spilling any grain. Will fit kettles up to 17" in diameter and will hold up to 20lbs of grain, thus makes the bag versatile enough for any application, from jams to cold brew to cider and fruit wine making, this bag can do it all!

Thermometer

For any homebrew you need a reliable and perfectly calibrated thermometer. A thermometer ensures you reach your target mash temperature, which is vital in homebrewing. You’ll also use it to measure your strike temperature, and you can use it to calculate your grain absorption rate. 

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Hydrometer

A hydrometer measures the density of a liquid. In homebrewing, you’ll use it to measure the gravity of your beer. Your beer’s gravity is an excellent way to measure your fermentation’s effectiveness because it shows you how much yeast is actually converting sugar to ethanol. 

Rhino Beer (0-32% Brix & 1.000-1.130 Specific Gravity) Refractometer for Homebrew and Automatic Temperature Compensation, Replaces Homebrew Hydrometer | Teflon Coating | Wine Fruit Juice Test
  • Rhino Beer Refractometer can replace your hydrometer because of easy and accurate measurements. Use the liquid sampler to take three or four drops of wort and put them on the prism. Then hold the refractometer up to the light source and look through the eyepiece. Due to the dual scale, there is no need convert the result into specific gravity as the scale measures both Brix and SG.
  • Rhino Beer Refractometer can measures 0-32% Brix and 1000-1.130 SG. It is suitable for measuring the proportion of beer or malt juice ( brewing ) or the fermentation process of brandy.
  • Rhino Beer Refractometer with Automatic Temperature Compensation ( 50°F - 86°F / 10°C - 30°C ).

Insulation Material 

Blankets, mats, or towels are all ideal to have around when using the BIAB method. They can help keep your brew kettle at the right temperature during mashing. Alternatively, you could use a large oven or outdoor smoker to help keep heat in the kettle. 

Tripod or A-Frame Ladder

It’s not required, but it is beneficial to have a tripod or A-frame with a hook or pulley system you can place over the brew kettle. You’ll use it as leverage when removing the brew bag. 

Alternatively, you could hoist the bag out with your own muscle, but remember you’re dealing with a hot and heavy load of wort that needs to drain for several minutes. Having some sort of leverage or lift makes the process far simpler and much safer. 

All-Grain Beer Recipe and Ingredients 

Finally, you’ll need a good all-grain beer recipe and all the ingredients it requires. Pick one that you find intriguing, and let’s get started! 

Step One: Prepare Your Brew Grains and Equipment

In homebrewing, the most important, albeit not the most glamorous, step is to sanitize your equipment.  

Once that’s set, for the BIAB method, you’ll want to ensure your grains are pre-crushed. Technically you can crush your malts yourself, but it’s easier to have your supplier do this for you. 

Step Two: Calculate Your Brew Batch

If math makes your brain spin, you can use a BIAB calculator to determine your brew batch. But in case you want to run the numbers yourself, we’ll go over it briefly here. 

Strike Water Calculations

Strike water is simply the liquid you add to your grains to create your mash. It varies based on your desired volume of wort. 

Regular homebrewing uses a standard 1-2 quarts of water per pound of grain, but with the Brew in a Bag method, you need to calculate your strike water exactly. To do this, you need to figure out your pre-boil volume first. 

That will get you your pre-boil volume. Simply multiply the boil time your recipe requires by the boil-off rate as determined by previous brews (or use 1 gallon per hour as a standard). Then add the final batch volume as indicated by your recipe. 

For example, if your recipe uses 12 lbs of grain, calls for a finished volume of 6 gallons, and the boil time is one hour, your calculation would look like this:

1 hour boil time x 1 gallon per hour boil-off rate + 6 gallons finished volume = 7 gallons pre-boil volume. 

From there, you can calculate your strike water as follows:

Grain Absorption Rate x Total Grain Weight + Pre-Boil Volume = Strike Water Volume 

The Grain Absorption Rate is typically .1-.125 per pound of grain, as a rule for homebrewers. So, using our example, we find: 

.125 x 12 + 7 = 8.5 gallons of strike water 

Finally, you need to know your strike water temperature. Typically, your strike water should be 8-12℉ above the mash rest temperature given in your recipe. Knowing and staying in this temperature range helps the yeast convert sugars to alcohol more efficiently, so you end up with delicious beer! 

Step Three: Make the Mash

Now comes the fun part. Making the mash is where the actual homebrewing begins. To start, add your strike water to the brew kettle and heat it to your target strike water temperature. 

Then add your brew bag. You can secure it using metal clips or whatever you have on hand. Just remember, you don’t want the bottom of the kettle to touch the bottom of the bag.

Next, add the ground malted grains to the bag, stir it and cover the concoction. Then take your thermometer and ensure you’re at the necessary mash rest temperature as indicated by your recipe. 

If your kettle is too hot, add ice to cool it down. If it’s too cold, try adding extra water until you reach the right temperature. 

Then, you remove the kettle from its heat source, wrap it in insulation or move it to a more insulated area, and let the mash rest. 

It’s hard, but try not to lift the lid or check the temperature while the mash is resting. Every time you lift the lid, you lose heat, which could be detrimental to your brew’s final quality. 

Step Four: Collect the Wort 

When you’re done resting the mash, you can lift the bag out of the kettle and allow it to drain. Drainage takes about 15 minutes, which is why having a ladder or A-frame to hoist and leverage the bag is helpful. 

If it feels like drainage is taking all day, you can help things along. Throw on some thick gloves and ask a friend for assistance. Between the two of you, you should be able to hold the bag steady over the kettle, then gently squeeze out the excess liquid. 

Once it’s done draining, empty the spent grains from the bag into a compost pile (or the trash), and rinse the bag for use next time. 

Then you can test your wort, which is what’s left in the kettle, for its original gravity using your hydrometer. If the gravity is too low, as indicated in your recipe, you can boil off some of the water to raise it. If it’s too high, you can add water to lower it. 

Final Steps

After step four, the process is precisely the same as producing any other extract or all-grain homebrew. You’ll boil your wort for 60-90 minutes; your recipe will give an exact time. And you’ll add hops when and as directed. 

Some recipes will have you use the brew bag you used for your grain to add your hops. The same rules apply; don’t let the bag touch the bottom or sides of the kettle to avoid scorching the hops! 

Finally, you’ll remove the hops, cool the wort, and pour it into a fermenting vessel of your choice. From there, it’s a simple waiting game. Eventually, you’ll have your very own craft brew to enjoy and share. 

So, see? Learning how to brew in a bag is ideal for anyone who wants a low-cost, easy method for producing beer at home. It’s as easy as brewing tea, and we think the results are at least twice as fun.