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Original gravity calculator from a grain bill

Wort gravity depends on grain potential, how much extract reaches your chosen measurement point and wort volume. Here, 5 kg of grain at 37 PPG, 75% recovery and 20 L gives approximately SG 1.058.

BrewMyBeer editorial · Sources checked 24 September 2026 · Calculated examples, not laboratory measurements. How we create content

Interactive tool

Calculate your batch

Change the example values. Inputs stay in your browser.

Total mashed grain weight.

Points per pound per US gallon; use a weighted average for mixed grains.

Measured or assumed recovery into the volume below.

Choose the same stage used for your efficiency measurement.

Choose a weighted potential for mixed grain

PPG means points per pound per US gallon. For multiple grains, multiply each grain’s weight by its PPG, add the products, then divide by total grain weight. Use supplier analysis or a documented ingredient database and record the assumption.

For example, 4 kg at 37 PPG plus 1 kg at 34 PPG gives (4 × 37 + 1 × 34) ÷ 5 = 36.4 PPG. A single average is convenient, but it should represent the actual bill.

Efficiency and volume must describe the same stage

Recovery into the kettle and recovery into the fermenter are different quantities because wort can be lost during boiling and transfer. Match the efficiency input to the volume you are predicting rather than mixing values from different stages.

The conversion factor 8.3454 combines kilograms to pounds and litres per US gallon. This tool estimates mashed-grain extract. Do not apply a mash recovery percentage to dissolved sugar or malt extract as if it were grain.

Before you use the result

  • Keep grain weights in kilograms and volume in litres.
  • Potential is not your actual measured recovery.
  • Validate the estimate against a mixed, temperature-corrected sample.

A quick learning check

With the same recovered extract, what does a larger final wort volume do?

Try a craft decision game →

Sources & further reading

These references explain the methods and limitations. The worked examples and learning questions on this page are BrewMyBeer calculations, not claims of hands-on testing.