BIAB (Brew In A Bag) Strike Water Calculator
Volume you want in the fermenter.
Total weight of all grains.
Standard BIAB is 0.6 – 1.0 L/kg.
Losses to sediment/hoses.
Brew Day Requirements
Total Strike Water Needed:
–
Estimated Pre-Boil Volume:
–
Water Lost to Grain:
–
Water Lost to Boiling:
–
Understanding BIAB Water Calculations
Brew In A Bag (BIAB) is a simplified all-grain brewing method that uses a single vessel for both mashing and boiling. Because there is no separate sparge step, you must start with the full volume of water required for your entire brew day.
Key Variables in BIAB Math
- Batch Size: This is your target volume of finished wort into the fermenter.
- Grain Absorption: When you lift the bag of grain out of the kettle, the grain retains a significant amount of water. For BIAB, where the bag is typically squeezed, this usually ranges from 0.6 to 1.0 liters per kilogram of grain.
- Boil-off Rate: This is the amount of water that evaporates during the boil. This varies based on kettle diameter and the intensity of your burner.
- Trub Loss: The volume of wort left at the bottom of the kettle (containing hop residue and proteins) that you don't transfer to the fermenter.
The BIAB Formula
To find your Total Strike Water, use this formula:
Total Water = Batch Size + Trub Loss + (Boil-off Rate × (Boil Time / 60)) + (Grain Weight × Grain Absorption)
Example Calculation
If you want 19 Liters of beer in your fermenter, using 5kg of grain, a 60-minute boil, and your equipment loses 3 Liters per hour to evaporation and 2 Liters to trub:
- Grain Loss: 5kg × 0.8 L/kg = 4 Liters
- Boil Loss: 3 Liters (1 hour boil)
- Total Strike Water: 19 (Target) + 2 (Trub) + 3 (Boil) + 4 (Grain) = 28 Liters
In this scenario, you would start your mash with 28 Liters of water.