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SRM Beer Color (Morey)

Predict your beer's SRM color from grain weight, color and volume.

How it is calculated

The tool applies the Morey equation in two steps. First the malt colour units: MCU = grain weight × Lovibond ÷ volume, with grain weight in pounds, colour in degrees Lovibond (°L) and batch volume in gallons. Then SRM = 1.4922 × MCU0.6859. Both results are shown to one decimal. There is only one grain entry, so a recipe with several malts must be reduced to a single weight and an effective colour (or the weight-times-colour products added together by hand and entered as one). A volume of zero or less, or a negative weight or colour, gives no result; a weight of zero gives 0.0.

Worked example

A batch uses 11 lb of grain at 20 °L and makes 5.5 gallons. MCU = 11 × 20 ÷ 5.5 = 220 ÷ 5.5 = 40.0. Raise 40 to the power 0.6859, which gives about 12.56. Multiply by 1.4922: 1.4922 × 12.56 ≈ 18.7. The tool shows an SRM of 18.7 and an MCU of 40.0, a deep amber to light brown colour. If the same grain went into a 7 gallon batch, MCU would fall to 31.4 and SRM to about 15.9.

Try this example →

Common mistakes

  • Entering the volume in litres or the weight in kilograms. The fields are pounds and gallons, so a 20 litre batch is about 5.3 gallons.
  • Entering the colour as EBC instead of Lovibond. EBC values are about double the Lovibond value, which gives a much darker prediction.
  • Using one malt's colour for a recipe that mixes pale base malt with a handful of dark roasted malt. Combine them first: weight × colour for each, added up, then divided by volume.
  • Treating the figure as exact. Morey's equation is a prediction, and it becomes less reliable for very dark beers.
  • Expecting the colour to double when MCU doubles. It does not, because of the 0.6859 power, so 40 MCU is not twice the SRM of 20.

About this calculator

The Morey equation estimates a beer’s color on the SRM (Standard Reference Method) scale from its grain bill: SRM = 1.4922 x (MCU^0.6859), where MCU (malt color units) equals grain weight in lbs times grain color in degrees Lovibond, divided by batch volume in gallons, summed across all grains in the recipe. The exponent corrects for the fact that color doesn’t scale linearly with malt color contribution at the darker end.

Homebrewers and craft brewers use SRM to predict what a beer will look like before brewing it — a pale lager sits around 2-3 SRM, an amber ale around 10-17, and a stout can run 30+ SRM (effectively opaque black past about 40) — which matters both for matching a style’s guidelines (BJCP style ranges reference SRM) and for choosing a grain bill that hits a target appearance. It’s a standard field in recipe-building software like BeerSmith and Brewer’s Friend.

This calculator takes the weight (in lb) and Lovibond color of a single grain plus your batch volume (in gallons) and returns the predicted SRM and MCU using the Morey formula. For a recipe with several grains, run each grain separately, add up their MCU values, and apply SRM = 1.4922 x (MCU^0.6859) to the total.

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