Brewhouse Efficiency: How to Calculate and Improve Yours

Brewhouse efficiency is one of the most direct levers on your cost of goods. A brewery running at 80% efficiency is using roughly 20% more malt than it needs to for every batch it produces. At scale, that is a significant and largely avoidable cost.

This article explains what brewhouse efficiency actually measures, how to calculate it, what good looks like for UK craft breweries, and the specific interventions that move the number.

What is brewhouse efficiency?

Brewhouse efficiency is the percentage of fermentable sugars extracted from your grain compared to the theoretical maximum available in that grain. In practical terms: if your malt contains 300 kg of fermentable extract and you capture 255 kg of it into the fermenter, your brewhouse efficiency is 85%.

It is not the same as mash efficiency (which measures only conversion in the mash tun) or fermentation efficiency (which measures attenuation). Brewhouse efficiency is end-to-end: grain in, wort out, measured at the point of pitching.

Why does it matter? Because malt is typically your single largest raw material cost. A 5-percentage-point improvement in brewhouse efficiency reduces malt spend by roughly the same proportion, across every batch, permanently.

How to calculate brewhouse efficiency: the formula

The standard formula is:

Brewhouse efficiency (%) = [(OG – 1) × 1000 × volume into fermenter (litres)] ÷ [grain weight (kg) × maximum extract points per kg] × 100

Maximum extract points per kg depends on the malt being used. For base malt, the figure is typically 300 to 310 points per kg (expressed as specific gravity points per litre per kg, or PPG in US units). Use the value from your malt supplier's specification sheet.

Worked example

Batch parameters: 500 litres into the fermenter, OG of 1.050, 100 kg of base malt (max extract 305 points/kg/litre).

Gravity points collected: (1.050 – 1) × 1000 × 500 = 25,000 points

Maximum possible points: 100 kg × 305 = 30,500 points

Brewhouse efficiency: 25,000 ÷ 30,500 × 100 = 82.0%

Calculate this consistently and you have a number you can track and improve. Many breweries calculate it per batch automatically once the formula is in their brew log.

Free brewhouse efficiency calculator

To make the calculation easier, Brew Resourceful offers a free brewhouse efficiency calculator in Excel format. Enter your OG, volume into fermenter and grain weight, and it calculates your efficiency and benchmarks it against industry averages automatically.

Download the free brewhouse efficiency calculator from the Brew Resourceful resources page.

The calculator also flags which efficiency band your brewery sits in, so you can see at a glance whether the gap is small (and addressable with process tweaks) or significant (and worth a more structured review).

What is a good brewhouse efficiency? UK benchmarks

Brew Resourceful's UK craft brewery benchmark is 81.7%, based on data from breweries that have completed a structured brewhouse efficiency review. In context, that means for every brew you run, a benchmark brewery captures 81.7% of the fermentable extract available in the grain. The spread across the industry is wide:

• Best in class: above 90%

• Good performance: 85 to 90%

• Industry average: 78 to 85% (Brew Resourceful benchmark: 81.7%)

• Significant opportunity: below 78%

Automated systems with integrated lautering and wort recovery tend to run toward the top of these ranges. Smaller direct-fire brewhouses, or systems without step-sparging capability, will typically sit in the 78 to 85% band even when well-operated. The benchmark that matters is one specific to your system type, not a generic average.

A figure above 96% in a craft context often indicates measurement error rather than exceptional performance. Check your volume measurements and gravity calibration first before assuming you have eliminated all losses.

The most common causes of low brewhouse efficiency

Most brewhouse efficiency losses fall into one of four areas. The order below reflects typical impact magnitude:

• Mash efficiency losses: poor crush quality, incorrect pH, incomplete conversion

• Lauter losses: channelling, premature sparge cutoff, slow runoff

• Kettle and trub losses: wort left in hops, trub cones and transfer hoses

• Measurement errors: inaccurate volume or gravity readings that make efficiency appear lower than it is

Mash stage losses

Poor crush is the most common cause of under-performance. Too coarse and you leave unconverted starch; too fine and you create a stuck lauter that forces you to cut the sparge short. The target is a clean husk with a fully cracked endosperm. Mash pH also matters: a pH of 5.2 to 5.4 produces optimal enzyme activity, and many breweries drifting to 5.6 or 5.7 are leaving 2 to 3 percentage points on the table. Mash temperature profile and rest time have a smaller but real effect on high-adjunct or undermodified grain bills.

Lauter stage losses

The lauter tun is where most breweries lose efficiency through one of two failure modes: a slow or stuck lauter that cuts the sparge early, or channelling that means the sparge water bypasses part of the grain bed. Vorlauf time, rake settings and grant management all affect lauter performance. The target runoff gravity at the end of the sparge tells you whether you left extract in the bed: anything above 1.008 to 1.010 at sparge cutoff suggests the bed was not fully washed.

Transfer and trub losses

Wort left in hop backs, kettle trub, transfer hoses and whirlpool cones is real loss. These are often fixed by better process discipline rather than capital investment: consistent whirlpool rest times, clear transfer protocols and accurate volume measurement at each stage. Hop absorption, particularly on highly dry-hopped beers, is unavoidable but can be quantified and factored into recipe design.

How Full Circle Brew Co improved from 88.1% to 95.8%

Full Circle Brew Co in Newcastle worked with Brew Resourceful on a structured brewhouse efficiency review. Starting from 88.1%, the project identified specific losses at mash, lauter and transfer stages and implemented process changes within existing equipment.

The result was 95.8% brewhouse efficiency, a 7.7 percentage point improvement. Over the year following implementation, that translated to 16,201 kg of malt saved and approximately £15,000 in annual raw material savings, with a measurable reduction in CO2e from the reduced malt processing requirement.

The interventions were primarily process-based rather than capital. Changes to crush settings, mash pH targets and lauter management protocols accounted for the majority of the gain.

How to improve brewhouse efficiency: practical fixes

The sequence below addresses the most impactful variables first. Work through them systematically rather than changing multiple things at once; you need to isolate cause and effect.

1. Measure first: calculate your current efficiency per batch for 4 to 6 brews to establish a reliable baseline before making any changes

2. Check your crush: invest in a grain crusher assessment or send a sample to your malt supplier for sieve analysis if you are not crushing in-house

3. Correct mash pH: target 5.2 to 5.4; test with a calibrated meter, not strips

4. Review mash temperature and rest time: most base malts are fully converted at 65°C in 60 minutes; extending rest time rarely adds more than 0.5 to 1 percentage point

5. Optimise the sparge: sparge volume and temperature matter; 76 to 78°C sparge water helps gelatinisation without extracting tannins

6. Monitor runoff gravity: stop collecting wort when the runoff falls to 1.008 to 1.010 unless a calculation shows the incremental extract is worth the dilution

7. Audit transfer losses: measure wort volumes at mash tun, kettle and fermenter to find where the unaccounted losses are occurring

When to get a brewery efficiency consultant involved

Process tweaks will typically recover 2 to 4 percentage points of brewhouse efficiency for most breweries. If you are consistently below 82% despite having corrected the obvious variables, or if your efficiency has declined without a clear cause, that is the point at which an independent review tends to find value.

A structured brewhouse efficiency audit looks at equipment performance (mill gap, mash tun heating uniformity, lauter tun geometry), process data (batch records, runoff gravity logs, trub volumes) and the measurement methodology itself. It is common to find that measurement inconsistency accounts for a significant portion of apparent inefficiency.

Full Circle improved 7.7 percentage points. Tooth and Claw recovered 11.5% of beer losses they did not know they were making. The common thread is that systematic review finds things that internal familiarity misses.

Book a free brewery efficiency review to find out where your brewhouse efficiency losses are occurring and what a realistic improvement target looks like for your specific system.