What is mash efficiency?

Mash efficiency (also called brewhouse efficiency when measured at the fermenter) is the percentage of the theoretical maximum sugar that you actually extracted from your grain bill and collected in the kettle. A reading of 75% means you got three-quarters of the available fermentable sugars into your wort. The rest stayed behind in the grain bed or was lost to dead space and absorption.

What is a good mash efficiency for homebrewing?

Most all-grain homebrewers land between 70% and 80%. Below 65% suggests a problem with crush, mash temperature, pH, or lauter flow. Above 85% is excellent and typical of fly-sparge setups with well-dialled equipment. Batch spargers usually see 72–78%; BIAB (Brew in a Bag) commonly runs 70–80% with a full-volume mash and a good squeeze.

What is PPG (Points Per Pound Per Gallon)?

PPG is the theoretical maximum gravity contribution of one pound of a grain dissolved in one US gallon of water, assuming perfect conversion and zero loss. It comes from laboratory hot-water extract (HWE) tests. Two-row pale malt is typically 37 PPG; adjuncts like flaked corn can be 39 PPG; dark roasted malts drop to 25–28 PPG because some starch has been converted to non-fermentable dextrins and colour compounds during kilning.

Should I use pre-boil or post-boil volume?

Use pre-boil volume with your pre-boil OG reading for the most accurate mash efficiency number — this isolates the mash and lauter steps from boil-off losses. If you measure post-boil OG and post-boil volume you will calculate brewhouse efficiency, which also bundles in losses to trub, hop absorption and chiller dead space. Both are useful; just be consistent so your numbers are comparable batch to batch.

How do I improve low mash efficiency?

The four biggest levers are: (1) grain crush — a tighter crush exposes more starch; (2) mash pH — aim for 5.2–5.4 for most styles; (3) mash temperature — 148–158 °F (64–70 °C) is the typical range; and (4) sparge technique — a thorough batch or fly sparge rinses more sugar from the grain bed. Thin mashes (higher water-to-grain ratio) also tend to improve conversion efficiency.

What is the difference between conversion efficiency and mash efficiency?

Conversion efficiency measures how completely your mash converted grain starch to fermentable sugar — a perfect conversion is 100%. Mash (or lauter) efficiency also accounts for how much of that sugar you successfully rinsed into the kettle. A mash can have excellent conversion but poor lautering, resulting in a lower combined efficiency. This calculator measures the combined effect because it compares the sugar collected in the kettle against the theoretical grain maximum.

Mash Efficiency Calculator

A brewing mash efficiency calculator for all-grain and BIAB homebrewers. Enter your grain bill with PPG values, your measured pre-boil OG and your wort volume and the tool instantly tells you your mash efficiency percentage, how many gravity points you actually collected versus the theoretical maximum, and how to correct your collection volume to hit any target gravity on your next brew day.

How it works

Mash efficiency is defined as:

Efficiency (%) = (Actual Points Collected) / (Maximum Possible Points) × 100

Step 1 — Maximum possible points. For each grain in your bill the calculator multiplies its weight in pounds by its PPG (Points Per Pound per Gallon). PPG is the laboratory-measured maximum extract assuming perfect hot-water conversion. For a 10 lb charge of 2-row pale malt at 37 PPG the maximum contribution is 370 gravity-points.

Step 2 — Actual points collected. Your OG reading is converted to gravity points: a reading of 1.052 becomes 52 points per gallon. Multiply by your collected volume in gallons and you have the total points sitting in the kettle. If you collected 5.5 gal at 1.052 you have 52 × 5.5 = 286 gravity-points.

Step 3 — Efficiency. Divide actual by maximum and multiply by 100. If your grain bill could theoretically give 370 points and you collected 286, your efficiency is 286 / 370 = 77.3% — a solid all-grain result.

Metric users can enter weights in kg and volumes in litres. Internally the calculator converts to US units for the PPG multiplication, then converts back for display — the result is mathematically identical.

Worked example

Recipe: American Pale Ale, targeting 5.5 gal at 1.052.

Grain	Weight (lb)	PPG	Max points
2-Row Pale Malt	10	37	370
Crystal 60L	1	34	34
Total	11		404

You collect 5.5 gal and measure pre-boil OG 1.049 (49 points):

Actual points = 49 × 5.5 = 269.5
Max possible = 404
Efficiency = 269.5 / 404 = 66.7% — below average

To hit 1.052 at the same 66.7% efficiency you would need to collect 5.5 × (49/52) × (52/49) — or simply use the built-in volume corrector, which gives 5.2 gal as your new target (you should not boil off as much, or sparge more thoroughly).

Formula note

The formula uses PPG as specified by the American Homebrewers Association and Brewer’s Friend convention. Metric equivalents use PPL (Points Per Litre) = PPG × 0.1198, but since the ratio (actual / max) is unitless the percentage is the same regardless of which system you use. If your malt supplier lists hot-water extract as a percentage (common in UK/European spec sheets), convert it with: PPG = HWE% × 46.2. Maris Otter at 81% HWE → 37.4 PPG, consistent with the 38 PPG used here.