Home › Food & Cooking › Beer Color (SRM) Calculator

Beer Color (SRM) Calculator

Predicts the colour of a beer from the grain bill: malt colour units (MCU) from grain weights, Lovibond ratings and batch volume, converted to SRM with the Morey equation, plus EBC, Lovibond, a descriptive colour name and an approximate hex colour.

When to use

You are designing a beer recipe and want its predicted colour in SRM or EBC, or need to check whether a grain bill matches a style's colour range.

Do not use when: The colour must be measured rather than predicted (SRM is defined by absorbance at 430 nm), or extract and adjunct colours are unknown; also unreliable above about 50 SRM where the Morey fit was not validated.

Formula

MCU = Σ(grain_weight_lb_i × grain_color_lovibond_i) / batch_volume_gal; SRM = 1.4922 × MCU^0.6859 (Morey); EBC = 1.97 × SRM; °L ≈ (SRM + 0.76) / 1.3546; 1 kg = 2.20462 lb, 1 US gal = 3.78541 L

Morey's power-law fit reproduces measured colour better than the linear MCU value, which overestimates dark beers; it is considered reliable up to about 50 SRM. Colour names are approximate bands (2–3 pale straw, 3–4 straw, 4–6 pale gold, 6–9 gold, 9–12 amber, 12–15 copper, 15–18 red-brown, 18–22 brown, 22–30 dark brown, 30–35 black, above 35 opaque black).

Inputs

ParameterTypeUnitRequiredDescription
batch_volumenumberyesFinal wort volume in volume_unit. Range: > 0, ≤ 100000
volume_unitenum: gal_us | ldefault gal_usUnit of batch_volume.
grain_weightsnumber_listyesWeight of each grain or extract in weight_unit, in order.
weight_unitenum: lb | kgdefault lbUnit of grain_weights.
grain_colors_lovibondnumber_list°LyesColour rating of each grain in degrees Lovibond (from the maltster), same order as the weights.

Outputs

OutputTypeUnitDescription
mcunumberMCUΣ(weight_lb × °L) / gallons.
srmnumberSRMStandard Reference Method colour from the Morey equation.
ebcnumberEBCEuropean Brewery Convention colour = 1.97 × SRM.
lovibondnumber°LApproximate Lovibond value = (SRM + 0.76) / 1.3546.
color_descriptionstringDescriptive colour name for the SRM band (pale straw to black).
hex_color_approxstringApproximate sRGB hex value for the nearest whole SRM (1–40) as used in homebrewing colour charts.

Example

5 gal: 10 lb at 2 °L + 1 lb at 40 °L: {"batch_volume":5,"volume_unit":"gal_us","grain_weights":[10,1],"weight_unit":"lb","grain_colors_lovibond":[2,40]} → {"mcu":12,"srm":8.2,"ebc":16.2,"lovibond":6.62,"color_description":"Gold","hex_color_approx":"#EA8F00"}

20 L: 4 kg at 3 °L, 0.5 kg at 120 °L, 0.25 kg at 500 °L: {"batch_volume":20,"volume_unit":"l","grain_weights":[4,0.5,0.25],"weight_unit":"kg","grain_colors_lovibond":[3,120,500]} → {"mcu":82.2,"srm":30.71,"ebc":60.5,"color_description":"Black"}

GET https://tttkmbb.com/api/v1/calculate/srm-color?batch_volume=5&volume_unit=gal_us&grain_weights=10%2C1&weight_unit=lb&grain_colors_lovibond=2%2C40

Machine access

Sources

FAQ

Where do I find a grain's Lovibond rating?

On the maltster's specification sheet; typical values are 1.5–3 °L for pale base malts, 10–120 °L for crystal malts and 300–600 °L for roasted malts. For EBC-rated European malts, °L ≈ (EBC / 1.97 + 0.76) / 1.3546.

Why does the descriptive name differ from a style guide?

Colour names are approximate bands; style guidelines such as the BJCP use their own slightly different band names, so compare the SRM number with the style's SRM range rather than the word.

Does extract brewing change the calculation?

No, but liquid and dry extracts have their own colour ratings (usually 2–4 °L for pale extract) and darken with long boils; use the manufacturer's value as the grain colour.

Related calculators