Pour two beers side by side and the first thing you judge, before the aroma and long before the first sip, is the colour. A pale straw lager and a jet-black stout look like completely different drinks, and brewers have a precise way to put a number on that difference. It is called the SRM scale. This guide explains what SRM measures, how beer gets its colour in the first place, where every style sits on the scale, and why the oldest myth in the pub, that dark beer is strong beer, is simply wrong. Every figure here is sourced, with a reference list at the bottom.
1. The SRM colour scale, from 2 to 40
SRM stands for Standard Reference Method, the colour scale used by brewers across North America. It runs from about 2 for the palest lagers up past 40 for an ink-black imperial stout. The lower the number, the more light passes through the glass; the higher the number, the darker and more opaque the beer[1]. Here is the full scale as a colour strip, with the numbers most people care about marked underneath.
The SRM scale rendered as a continuous colour gradient, SRM 1 (pale straw) to 40 (opaque black). Approximate on-screen colours; a real beer also has clarity and hue that a single number cannot capture. Source: standard SRM colour reference.
Broken into the bands you will actually see on a beer menu, it looks like this. The example beers are typical, not fixed, since brewers move within a style.
A quick reality check on the scale: it is a measure of colour density, not hue[3]. Two beers can share an SRM number and still look slightly different in the glass, one leaning red, another leaning brown, because SRM squeezes a full colour into one figure. It is a brilliant shorthand, not a perfect fingerprint.
2. How beer colour is actually measured
The number is not a guess or a paint chart. A brewer or lab shines a beam of deep blue light at a wavelength of 430 nanometres through a sample of beer held in a one centimetre cell, then measures how much of that light is absorbed[1]. The darker the beer, the more light it soaks up. That absorbance is multiplied by a fixed constant, 12.7, to give the SRM number.
The method dates to the 1950s, when the American Society of Brewing Chemists standardised it so any two labs would report the same colour for the same beer[5]. It replaced an older visual system, the Lovibond scale, where a technician matched the beer against tinted glass slides by eye. SRM was designed so that, at the pale end, its numbers line up closely with those old Lovibond degrees, which is why you still see Lovibond quoted on bags of malt today.
3. SRM vs EBC vs Lovibond
If you read European brewing sources or a homebrew recipe from the UK or Germany, you will meet a second scale: EBC, the European Brewery Convention colour. It measures the same 430nm absorbance but scales it differently, so an EBC number is roughly double the SRM number for the same beer[2]. Lovibond is the third name you will see, mostly on malt. The conversions are simple.
| Scale ↕ | Region ↕ | Rule of thumb ↕ | Example (amber ale) ↕ |
|---|---|---|---|
| SRM | North America | Absorbance x 12.7 | 12 SRM |
| EBC | Europe | EBC = SRM x 1.97 | 24 EBC |
| Lovibond | Malt spec | L = (SRM + 0.76) / 1.3546 | 9.4 L |
Tap any column heading to sort.
Beer colour scale conversions. EBC is about twice SRM; Lovibond tracks SRM closely at the pale end. Source: Craft Beer & Brewing colour calculator.
The short version: same beer, three numbers. A 12 SRM amber ale is a 24 EBC amber ale is a 9.4 Lovibond amber ale. If a European recipe looks alarmingly dark next to an American one, check whether it is quoting EBC before you assume anything.
4. What gives beer its colour
Almost all of beer colour comes from one ingredient: the malt. Not the hops, not the yeast, not the water. Malted grain, usually barley, is dried and heated in a kiln, and the amount of heat it takes decides how dark the finished beer will be[6]. A little gentle warmth leaves the grain pale gold. Push the kiln hotter and longer and the grain turns amber, then brown, then almost black.
Maillard browning and roasting
Two chemical processes do the work. The first is the Maillard reaction, the same browning that colours toast and seared steak, where sugars and amino acids in the grain react under heat to form brown pigments called melanoidins. This gives crystal and Munich malts their amber-to-copper tones and a bready, caramel flavour[6]. The second, at the very dark end, is outright roasting, which chars the grain husk and produces the near-black colour and coffee-and-chocolate bitterness of a stout. It is closer to roasting coffee beans than to toasting bread.
Big commercial brewers can nudge colour with additives such as caramel colouring, but the honest route, and the one craft and traditional brewers stick to, is choosing the malt. That is why colour and flavour travel together: the same roasting that darkens the beer is what puts the coffee note in your stout.
5. Beer styles by colour
Here is where the common beer styles land on the SRM scale, from palest to darkest, using the ranges in the widely used BJCP style guidelines[3]. Tap any heading to sort. The colour chip shows the middle of each range.
| Style ↕ | SRM range ↕ | EBC range ↕ | Colour ↕ |
|---|---|---|---|
| American light lager | 2 to 3 | 4 to 6 | pale straw |
| Pilsner | 2 to 5 | 4 to 10 | straw |
| Witbier | 2 to 4 | 4 to 8 | pale straw |
| Hefeweizen | 3 to 6 | 6 to 12 | straw gold |
| Blonde ale / Kolsch | 3 to 6 | 6 to 12 | pale gold |
| Saison | 5 to 14 | 10 to 28 | gold to amber |
| American pale ale | 5 to 10 | 10 to 20 | gold |
| American IPA | 6 to 14 | 12 to 28 | gold to amber |
| Marzen / Oktoberfest | 8 to 17 | 16 to 33 | amber |
| Amber ale | 10 to 17 | 20 to 33 | copper |
| Vienna lager | 9 to 15 | 18 to 30 | copper |
| Bock | 14 to 22 | 28 to 43 | light brown |
| Brown ale | 18 to 30 | 35 to 59 | brown |
| Munich dunkel | 14 to 25 | 28 to 49 | brown |
| Schwarzbier | 17 to 30 | 33 to 59 | dark brown |
| Porter | 20 to 30 | 39 to 59 | dark brown |
| Dry / Irish stout | 25 to 40 | 49 to 79 | black |
| Imperial stout | 30 to 40+ | 59 to 79+ | opaque black |
Tap any column heading to sort.
Typical SRM colour ranges by beer style. EBC is SRM x 1.97; chip shows the mid-range colour. Source: BJCP 2021 style guidelines.
The pattern is clear: lagers and wheat beers cluster at the pale end, pale ales and IPAs sit in the gold-to-amber middle, and the porters and stouts own the dark end. But notice how much the ranges overlap. An amber IPA and a Marzen can be the exact same colour and taste nothing alike, which brings us to the biggest misconception about beer colour.
6. Does darker beer mean stronger or more bitter?
No. This is the most common belief about beer, and it is simply not true. Colour comes from the malt and the kiln. Alcohol comes from how much sugar the yeast ferments. Bitterness comes from the hops. All three are set independently, so a beer can be any combination of dark, strong and bitter, or none of them[4].
The clearest proof is in the two most famous beers on Earth. Near-black Guinness Draught is only about 4.2% ABV, lighter in alcohol than pale golden Budweiser at around 5%[4]. Meanwhile a Belgian tripel is a bright golden colour and hides about 9% ABV, and a pale German maibock can top 8%. If you judged strength by colour you would get every one of these backwards.
Colour does not predict strength: a near-black stout can be weaker than a pale lager. Source: The Oxford Companion to Beer.
The same goes for body and bitterness. Plenty of dark beers, an Irish dry stout or a dark mild, are light-bodied and easy drinking, with the roasted colour doing the heavy lifting on flavour rather than alcohol. So use colour for what it is good at, a fast guide to malt character and roast, and never as a shortcut for how strong or how bitter the beer will be.
Want the numbers behind the drink? Our global beer statistics page covers the strongest beers ever made, alcohol content by style, and how much a pint costs around the world. And if the morning after ever catches up with you, our evidence-led guide to hangover cures sorts the real fixes from the folklore. If you want to see how those styles come to exist in the first place, our how beer is made guide breaks down the brewing process.
7. Frequently asked questions
What is the SRM scale in beer?
SRM stands for Standard Reference Method, the scale brewers use to measure beer colour. It runs from about 2 for the palest lagers to over 40 for an opaque black stout. The number comes from shining 430nm blue light through a sample and measuring how much is absorbed, then multiplying by 12.7.
What is the difference between SRM and EBC?
They measure the same thing, beer colour at 430nm, but on different scales. EBC is the European standard and is roughly double the SRM value. To convert, EBC = SRM x 1.97, so a 10 SRM beer is about 20 EBC. Lovibond is a third, older scale used mainly for malt and tracks SRM closely at the pale end.
What gives beer its colour?
Almost entirely the malt. Malted grain is dried in a kiln, and the more heat it gets the darker it becomes, through Maillard browning at moderate heat and outright roasting at high heat. Hops, yeast and water contribute almost nothing to colour.
Does a darker beer have more alcohol?
No. Colour and alcohol are unrelated. Colour comes from the malt and the kiln; alcohol comes from how much sugar the yeast ferments. Near-black Guinness is only about 4.2% ABV, lighter than pale Budweiser at around 5%, while a golden Belgian tripel can be 9%.
Does darker beer mean more bitter?
Not necessarily. Bitterness comes from hops and is measured separately in IBU. A dark stout can be smooth and low in bitterness while a pale IPA can be intensely bitter. Roasted dark malts add their own roast bitterness, but that is different from hop bitterness and does not follow colour reliably.
What SRM is a stout?
A dry Irish stout is usually around 25 to 40 SRM and an imperial stout 30 to 40 or higher, which is why they look black in the glass. At that darkness the beer is effectively opaque and only shows colour at the very edge when held to a light.
What SRM is a lager or pilsner?
Pale lagers and pilsners sit at the light end, around 2 to 5 SRM, which is the straw-to-gold colour most people picture when they think of beer. American light lagers can be as pale as 2 SRM.
How is beer colour measured in a lab?
A spectrophotometer shines light at a wavelength of 430 nanometres through a one centimetre sample of beer and measures the absorbance. SRM equals that absorbance multiplied by 12.7. Very dark beers are diluted with water first, then the reading is scaled back up.
Sources and references
- Wikipedia, Standard Reference Method (SRM), citing ASBC Methods of Analysis
- Craft Beer & Brewing, Beer Color Converter (SRM, EBC, Lovibond)
- BJCP 2021 Style Guidelines, Colour Reference and style vital statistics
- The Oxford Companion to Beer, entry: colour
- Grainfather / ASBC, Calculation of Beer EBC and SRM history
- Briess Malt & Ingredients, Malt colour, kilning and the Maillard reaction
Colour ranges and conversions reviewed against the BJCP guidelines and ASBC method. On-screen swatches are approximate; a printed or backlit beer will vary. Reviewed August 2026.
