Brew In A Bag (BIAB)

Originally presented as the education topic of the April 2017 meeting by Tyler and Perrin.

Homebrewing is historically categorized into two approaches: Extract or all grain brewing. 

Extract brewing utilizes a concentrate malt extract as the primary source of fermentable in the wort. Extract brewing can be conducted with a single vessel. Extract brewing also lets you customize your beer by utilizing different syrups, dry extracts, additives and hop and yeast addition.

All grain brewing starts with grains, and through the process of mashing, converts the starches to sugars used in fermentation. Moving from extract to all-grain  (AG) brewing to all-grain allows for fine-tuning, and a bit more control of your beer down to the milling of grain, and mashing temps and time.

Usually all grain brewing utilizes multiple vessels for the hot liquor, mash tun and boil kettle. The need for extra hardware and equipment are primary reasons why some prefer extract brewing.

This is where Brew In A Bag (BIAB) methodology comes in.

What is BIAB?

BIAB is a brewing method that has been growing in popularity. Rumored to have originated in Australia, BIAB brewing is all grain brewing in it’s simplest form.

Instead of requiring separate vessels for HLT, MT and BK, this technique can be performed with only one kettle. By reducing the cost of entry, BIAB brings all grain brewing to all brewers.

In BIAB, the grains are milled and put inside of a bag which is submerged in the hot liquor for ~60 minutes (the mash).



  • Kettle
  • Bag (More on that)
  • Hops
  • Heat Source
  • Brute strength (and other options?)
  • Chilling Method


  • Pump
  • Secondary vessel for sparging
  • Pulley system or extra muscle

The Bag

The bag itself is fairly simple, there are a few commercial options


  • Choose your recipe!
  • Be sure your bag can hold the grains
  • Heat up your strike water for the mash

Initial Infusion Equation:

Strike Water Temperature Tw = (.2/r)(T2 – T1) + T2

Mash Infusion Equation:

Wa = (T2 – T1)(.2G + Wm)/(Tw – T2)


r = The ratio of water to grain in quarts per pound.

Wa = The amount of boiling water added (in quarts).3. Fit your bag into your kettle. Clamps or ties can be helpful

  •  Add your [milled] grains
  • Make sure your grains are mixed with water thoroughly
  • Allow time for starch conversion
    • Advanced technique: use a pump to recirculate the mash over the bag
  • Lift the bag from the kettle and drain all the precious wort
    • Advanced technique: add a gallon of hot (168F) water to the bag to rinse any remaining sugars off (pseudo sparge)
  • Boil, add hops, chill, ferment per usual
  • Brew. Drink. Repeat.


With BIAB, any brewer can brew all grain.This gives you the opportunity to be more in control of your finished product.


  • Lower cost of entry, only one kettle needed
  • Without a sparge, fewer heating costs
  • Quicker brew day than typical all grain; less to clean
  • Customization beyond extracts
  • Bag is reusable


  • Recipe is limited by bag/kettle size
  • Longer brew day than extract
  • You can scorch the bag if you’re not careful…making for a tricky brew day


Resources: (AHA members only)