The Brewer

Brewhouse Efficiency: How to Calculate and Improve It

Brewhouse Efficiency: The Metric That Matters

“I missed my gravity.” It is the most common complaint among homebrewers. You aimed for an IPA with an Original Gravity (OG) of 1.065, but you ended up with a watered-down 1.050. Why?

The answer lies in Efficiency. Efficiency is simply a measure of how much sugar you successfully extracted from the grain compared to the theoretical maximum potential of that grain.

The Three Types of Efficiency

To fix your efficiency, you need to know where you are losing sugar.

1. Conversion Efficiency (The Mash)

Did you actually turn the starch into sugar?

  • The Test: Iodine Test.
  • The Cause: Poor crush, bad pH, mash temp too high/low, not mashing long enough.
  • Goal: close to 100%.

2. Lauter Efficiency (The Rinse)

Did you wash the sugar out of the grain and into the kettle?

  • The Cause: Channeling (water finding the path of least resistance), sparging too fast, dead space in the mash tun.
  • Goal: 70-80% (Fly Sparge) or 65-75% (Batch Sparge).

3. Brewhouse Efficiency (The Whole System)

This takes into account the volume losses. It is the number you put into Brewfather/Beersmith.

  • The Calculation: Sugar in the Fermenter / Potential Sugar in the Grain.
  • The Cause: Trub loss in the kettle, wort left in hoses/pumps/chillers.

How to Improve Efficiency

1. The Crush

This is the #1 culprit. If your grain is not crushed enough, the water can’t get to the center of the kernel.

  • Fix: Tighten your grain mill gap. You want the husks intact (for a filter bed) but the inside to be gritty flour.
  • The Risk: If you crush too fine, you might get a “Stuck Mash” (clog).

2. Mash Mixing

Dough balls are dry pockets of grain that never touch water.

  • Fix: Whisk your mash vigorously when you dough in. Break up every clump.

3. Sparge Speed

If you fly sparge (sprinkle water on top while draining), you must go slow.

  • Fix: It should take 45-60 minutes to drain the mash tun. If you rush it, the water just runs over the grain without washing out the sugar.

4. Dead Space

If your kettle or mash tun has a dip tube that sits 1 inch above the bottom, you are leaving liters of sugary wort behind.

  • Fix: Install a pickup tube that scrapes the bottom, or tilt the vessel to get every last drop.

Consistency > High Efficiency

Don’t obsess over getting 90% efficiency. Commercial breweries often aim for lower efficiency (85%) because pushing for that last 5% often extracts tannins and harsh flavors (over-sparging).

The goal is Consistency. If you know your system always hits 68% efficiency, you can adjust your recipe (add a handful more grain) and hit your target gravity every single time. Predictability is the mark of a pro.