Beer Color SRM Calculator — Morey Formula with Style Chart

The Morey equation (Daniel Morey, 1993) is SRM = 1.4922 × MCU^0.6859, where MCU = Σ(lbs × °L) ÷ gallons for each malt in the grain bill. It was curve-fit against thousands of real commercial and homebrewed beers and captures the non-linear relationship between grain bill color and final beer color far better than the older linear Mosher (SRM = 0.3 × MCU + 4.7) or Daniels (SRM = 0.2 × MCU + 8.4) formulas. For homebrewing and small craft production, Morey is accurate within ±1–3 SRM across the full spectrum. It's the default in BeerSmith, Brewer's Friend, and most recipe software.

The conversion factor is EBC = SRM × 1.97 (or SRM = EBC ÷ 1.97). Key reference points: 5 SRM = 9.9 EBC (American Pale Ale); 14 SRM = 27.6 EBC (IPA / Amber Ale); 35 SRM = 69 EBC (Stout). European recipes and malt specifications (especially German and British) use EBC; American homebrewing literature uses SRM. This calculator outputs both side by side.

MCU (Malt Color Units) is the intermediate value in the Morey formula. For each malt: MCU = (weight in lbs × Lovibond °L) ÷ batch volume in US gallons. Sum MCU across all malts before applying the Morey equation. Example: 8.8 lbs (4 kg) of 2°L Pale Malt in 5.28 gal (20 L) = (8.8 × 2) ÷ 5.28 = 3.33 MCU. Add 0.66 lbs (0.3 kg) Crystal 60L: (0.66 × 60) ÷ 5.28 = 7.5 MCU. Total MCU = 10.83 → SRM = 1.4922 × 10.83^0.6859 ≈ 8.2 SRM. This calculator handles kg→lbs and L→gallons automatically.

Yes — the Morey formula only models malt contributions. Maillard browning reactions during the boil add approximately 1–3 SRM per 60-minute boil and up to 4 SRM at 90 minutes. High-gravity wort and vigorous rolling boils amplify this. For very pale beers (under 5 SRM: Pilsner, Light Lager, Kölsch), target 1–2 SRM below your desired result when designing the grain bill, as the boil will add the remainder. For a Scottish Ale where caramelization is stylistically intentional, a longer boil is a valid color-deepening technique.

Typical ranges: Base malts — Pilsner 1.5–2°L, Pale 2-row 2°L, Vienna 4°L, Munich 8–10°L, Maris Otter 3–4°L, Wheat Malt 2–3°L. Crystal malts — Crystal 10L/20L/40L/60L/80L/120L at their label value; Caramunich I 25°L, Caramunich III 55°L; Special B ~180°L. Roasted malts — Biscuit/Victory 25–35°L, Chocolate Malt 300–400°L, Roasted Barley 300°L, Black Patent 500–525°L, Carafa Special III ~525°L. Always verify with your malt supplier's spec sheet — significant variation exists between maltsters.

Factors that darken beyond prediction: longer boil times, high mash temperatures (above 158°F/70°C), low mash pH (below 5.2), scorching, high-gravity concentration, oxidation. Factors that lighten: cold-side fining agents (gelatin, isinglass), filtration, high adjunct additions (rice, corn, sugar), highly flocculent yeast. Practical rule: add 1–2 SRM to the Morey output for any recipe with a 60+ minute vigorous boil. Calibrate against measured results from previous batches on your specific system.

Yes. Use the Lovibond rating of your malt extract as the 'base malt' input: Pilsen LME ≈ 2–3°L, Extra Light DME ≈ 3°L, Amber LME/DME ≈ 10–15°L, Dark LME/DME ≈ 20–30°L, Munich LME ≈ 8–10°L. For partial mash with steeping specialty grains, add them in the crystal or roasted fields. Note: Liquid Malt Extract (LME) often runs 1–3 SRM darker than the Morey prediction due to processing.

Key BJCP 2021 SRM ranges: Light Lager 2–3, German Pilsner 2–5, Kölsch 3.5–5, Blonde Ale 3–6, American Pale Ale 5–10, American Wheat 3–6, American IPA 6–14, American Amber Ale 10–17, California Common 10–14, Märzen 8–17, Vienna Lager 9–15, Bock 14–22, Doppelbock 6–25, Weissbier 2–8, Dunkelweizen 14–23, American Brown Ale 18–35, English Porter 20–30, American Porter 22–40, American Stout 30–40, Russian Imperial Stout 30–40, Schwarzbier 17–30, Flanders Red Ale 10–17. SRM is part of the BJCP Appearance scoring (3 of 50 points).

Lab measurement: SRM = 12.7 × D × A430, where D is the dilution factor and A430 is absorbance at 430 nm using a spectrophotometer with a 0.5 cm cell. In practice, commercial breweries measure SRM spectrophotometrically on every batch for QC. Homebrewers and recipe designers use the Morey formula to predict SRM from the grain bill before brewing, then optionally verify visually against BJCP SRM color cards post-fermentation. The Morey prediction is sufficient for recipe compliance — lab measurement is only needed for tight commercial tolerances or contract brewing.