Mash & Brewhouse Efficiency Calculator
Work out your mash / brewhouse efficiency from a measured gravity and your grain bill.
Original gravity you actually read
Grain bill
-% efficiency
Interpretation-
How it works
Efficiency is the ratio of the gravity you actually got to the maximum the grain bill could yield. The denominator is the total extract potential; the numerator is the gravity points you captured in your measured volume.
efficiency % = (measured points × volume_gal) / Σ(PPG × weight_lb) × 100
Sources: efficiency math as documented by Brewer's Friend; John Palmer, How to Brew §2.
Garbage in, garbage out: an accurate result needs a calibrated, temperature-corrected gravity reading and a true volume measurement.
Frequently asked questions
- How do you calculate mash (brewhouse) efficiency?
- Compare the gravity you actually measured against the maximum the grain could give. Multiply your measured OG points by the batch volume in gallons to get the points you captured, divide by the sum of each grain’s PPG times its weight in pounds, and express it as a percentage.
- What is a good efficiency number?
- Most all-grain homebrew systems land between 70% and 80%. Batch-sparge and BIAB setups often sit a little lower; fly-sparging with a fine crush can push higher. Consistency matters more than the absolute number - once you know yours, your OG predictions get accurate.
- Is this mash efficiency or brewhouse efficiency?
- This computes efficiency at the point where you took the OG reading. If you measure into the fermenter using the post-boil volume, you get brewhouse efficiency (includes kettle and trub losses). Measure pre-boil to isolate conversion plus lauter (mash) efficiency.