ABV, IBU and SRM Explained: The Numbers on Your Tap List

ABV is the share of the liquid that is ethanol. IBU counts isomerized hop acids in a lab. SRM measures how much deep blue light the beer absorbs. Only one of the three is regulated, and federally it is still optional on most beer labels - the TTB has proposed changing that, but the rule is not final. The practical order for an operator is ABV first, IBU with context, SRM almost never on a chalkboard. This guide covers what each number measures, why IBU misleads drinkers, what the TTB actually requires, and where each spec should live.

Introduction: Your Tap List Is a Search Result Before It Is a Menu

Walk into most taprooms and the chalkboard reads the same way. Beer name, style, ABV, IBU, sometimes SRM, sometimes a color swatch. Nobody decided that layout. It got copied from the last place the owner worked, and the one before that.

Then the same string of numbers gets typed into the website, unchanged, as plain text inside a paragraph.

That second copy is the one that matters. A drinker standing at your bar can ask the bartender what the IBU means. A drinker sitting on the couch at 7pm searching for a low-alcohol option near them cannot, and neither can the assistant answering on their behalf.

So the specs are doing two jobs at once. On the wall they help someone choose. On the website they are structured data that decides whether you show up at all. Those two jobs want different things, and treating them as one is why so many brewery beer pages are a wall of numbers nobody can act on.

Beer page reviews are a standing item in BeerSoft onboarding, and the tap list is where they usually stall. The numbers are rarely wrong. They are sitting on a surface that cannot use them.

Here is what each number actually is, and where it belongs.

What Do ABV, IBU and SRM Actually Measure?

Three different things, measured three different ways, with three very different levels of usefulness to a customer.

ABV is alcohol by volume - the percentage of the liquid that is ethanol. A brewer usually derives it from gravity readings taken before and after fermentation rather than from direct analysis. CraftBeer.com's study guide gives the working approximation: subtract final gravity from original gravity and divide by 0.0075. A beer that starts at 1.050 and finishes at 1.012 lands near 5.1%.

IBU is International Bitterness Units, and it is a concentration, not a flavor score. One IBU is one milligram of isomerized hop alpha acids per liter of beer. It comes out of a spectrophotometer, not a tasting panel.

SRM is the Standard Reference Method, adopted by the American Society of Brewing Chemists in 1950. A photometer measures how much light at 430 nanometers - deep blue, near violet - is absorbed passing through a centimeter of beer. Scale that absorbance and you get the SRM number. It runs from about 2 for a pale straw lager to 40 and above for something genuinely black.

The thing worth internalizing is that these are not three flavors of the same measurement. ABV is a proportion. IBU is a concentration. SRM is an optical property. Only one of them is something a customer has an existing mental model for.

Key Takeaway: ABV is the only one of the three that changes a customer's decision before they can see or taste the beer. Lead with it everywhere.

Is your beer page findable? Request a free digital audit and we'll show you which of your beers are turning up in search and which are invisible.

Why Doesn't the IBU Number Match What People Taste?

Because IBU measures a compound and bitterness is a perception, and the gap between them is wide enough that the Brewers Association writes the warning into its own style guidelines.

Open the 2026 Beer Style Guidelines - released in January 2026, with Rice Lager as the new addition - and read the Hazy IPA entry. Bitterness is listed at 5 to 30 IBU, followed immediately by the note that it may differ significantly from perceived bitterness. The organization that publishes the number tells you not to trust it alone.

Two things break the link. The first is that most people cannot resolve the ends of the scale at all. CraftBeer.com's guide puts the perceptible band at roughly 8 to 80 IBU; below 8 there is nothing to detect, and past about 80 the palate stops registering the increase. A 100 IBU double IPA and an 80 IBU one taste the same amount of bitter to almost everybody. The number went up. The experience did not.

The second is balance. Residual sugar, body and malt sweetness all push against bitterness. Ray Daniels, who created the Cicerone certification program, formalized this as the BU:GU ratio - divide the IBU by the last two digits of the original gravity. Around 0.5 reads as balanced, lower reads sweeter, higher reads more bitter. A pale ale at 37 IBU with an OG of 1.052 gives 37/52, or 0.71, and drinks noticeably bitter. Take the same 37 IBU and put it in a stout at 1.070 and you get 0.53, which lands as balanced.

That last row is the one that settles the argument. A dry stout at 40 IBU reads more bitter than a hazy IPA at 30 does, and the hazy is carrying several times the hop load. IBU alone told you nothing.

The version of this we see most often is a taproom printing IBU on every line of the chalkboard because the POS field exists, then watching servers spend the shift explaining that the 65 IBU one is actually the easier drinker. That is a menu creating work for the staff.

Swapping that bare figure for a word is the default first move BeerSoft makes on a taproom menu. It costs nothing to print and it takes the explanation off the server.

Key Takeaway: IBU is a lab result. Bitterness is an opinion. If you print IBU at all, print a word next to it - soft, firm, sharp - because the word is what the customer is actually buying.

What Does the TTB Actually Require You to Print?

Less than most operators assume, and that is about to be worth watching.

For a straightforward beer, a federal alcohol content statement is optional. The TTB requires one only when the malt beverage takes alcohol from an added flavor or other added nonbeverage ingredient - hops extract excepted - under 27 CFR 7.63(a)(3). Everything else is down to state law. It was not always even permitted: the Federal Alcohol Administration Act originally banned ABV statements on beer labels outright, and the Supreme Court struck that ban on First Amendment grounds in Rubin v. Coors Brewing Co. in 1995.

When you do print it, the formatting rules are specific and a few of them surprise people:

• The abbreviation "ABV" is not permitted on the label. Only "alc." and "vol." may be abbreviated. The chalkboard is not a label, so this bites on packaging, not the wall.
• No ranges, no maximums, no minimums. One number.
• At 0.5% and above, the statement goes to the nearest tenth of a percent.
• There is a tolerance of 0.3 percentage points either side of what you printed.

That tolerance line is the one worth sitting with. A beer labeled 6.0% can legally test anywhere from 5.7% to 6.3%. The number on your menu was never a precise claim, and the TTB has never treated it as one.

Now the part that is live. In January 2025 the TTB published Notice No. 237, proposing an "Alcohol Facts" statement on every alcohol beverage label - and, separately, mandatory alcohol content statements for all malt beverages and beers. It also proposed widening the tolerance from 0.3 to a full percentage point, on the argument that small brewers cannot afford the equipment to hold 0.3. The Brewers Association backed mandatory ABV on exactly that condition; the Beer Institute opposed the wider tolerance as misleading. Comments closed with 1,880 on the docket. It is still a proposal, and the proposed compliance window is five years from whenever a final rule lands.

Note what is absent from that table. IBU and SRM are not regulated anywhere. Nobody audits them, nobody enforces them, and a brewery can print whatever its recipe software calculated. That is not an argument for sloppiness - it is an argument for deciding what those two numbers are for, since no regulator has decided for you.

Key Takeaway: ABV is the only spec with a rulebook, and today that rulebook still makes it optional. If you sell an NA beer, the adjacency requirement on "contains less than 0.5% alcohol by volume" is the compliance detail most likely to catch you out.

Planning packaging or a website refresh in the next year? Talk to us about your beer pages before the Alcohol Facts rule lands, not after.

Which Numbers Belong on the Chalkboard, the Menu, and the Website?

Different surfaces, different jobs, and the mistake is running the same string of specs across all three.

The chalkboard is read standing up, in low light, by someone who has already committed to buying a beer. It has room for a handful of characters per line. ABV earns its place because it changes what someone orders and how many. IBU earns a place only if you replace the bare number with a word. SRM earns nothing - the beer is right there, and the customer can see it.

SRM is the most precise number on your tap list and the least useful one on your chalkboard. It is a lab-grade optical measurement of something the customer's eyes already told them.

The printed menu has more room and a different reader - often someone eating, comparing, taking longer. This is where a bitterness word plus a food pairing does more work than either number alone.

The website is the one that behaves differently from both, because its reader is frequently not a person. It is a crawler building an index, or an assistant assembling an answer to "low alcohol beer near me." That reader cannot infer anything. It needs the beer's name, style, ABV and description as distinct labeled fields, not as a sentence.

Key Takeaway: Strip SRM from the chalkboard and give the space to a bitterness word. Keep all three on the beer page, where the extra field costs nothing and completes the record a machine is reading.

How Do You Publish These Numbers So AI Search Can Cite Them?

By giving every beer its own URL and putting the specs in labeled fields rather than prose.

The common failure is a single /beers page listing twelve beers as paragraphs. To a crawler that is one document about twelve things, and it will not reliably answer a question about any one of them. One beer, one page, with the name in the H1 and the specs in a definition list or a table, is the structure that survives being parsed.

Then mark it up. Product schema carries name, description and brand cleanly. The three specs go in additionalProperty as PropertyValue entries, each with an explicit name, value and unit - that is what turns "5.2" into "5.2% ABV" for something that cannot read context. Pair it with LocalBusiness on the taproom page so the beer and the place are connected.

Two habits that matter more than the markup itself. Answer in the first sentence: a page that opens "Ridgeline is a 5.2% West Coast pale ale" is quotable, while one that opens with three sentences of brewery origin story is not. And retire the pages for beers you no longer brew, or redirect them to what replaced them - a live page for a beer that has not been on tap since spring is a wrong answer waiting to be given on your behalf.

This is the part of the job our AI search optimization work exists for, and it is the part most brewery sites skip entirely.

Key Takeaway: One beer, one URL, specs in labeled fields, Product schema with additionalProperty for ABV, IBU and SRM. Then delete the pages for beers you have retired.

Frequently Asked Questions

What does ABV mean on beer?

ABV stands for alcohol by volume - the percentage of the liquid that is ethanol. A 5% ABV pint is 5% alcohol by volume. Brewers usually calculate it from gravity readings taken before and after fermentation rather than measuring it directly. Federally, the TTB permits a tolerance of 0.3 percentage points either side of the figure you print, so a beer labeled 6.0% may legally test between 5.7% and 6.3%.

Is a higher IBU always more bitter?

No. IBU counts isomerized hop acids in a lab, and perceived bitterness depends just as much on residual sugar, body and malt sweetness. Most people cannot detect differences below about 8 IBU or above about 80. A dry stout at 40 IBU often reads sharper than a hazy IPA at 30, because the hazy carries more sweetness to balance it.

Does my beer label legally need an ABV percentage?

Usually not, federally. The TTB requires an alcohol content statement only when the malt beverage derives alcohol from an added flavor or other nonbeverage ingredient, other than hops extract. State law may require it independently. The TTB has proposed making ABV mandatory on all beers under Notice No. 237, but that rule is not final and carries a proposed five-year compliance window.

What SRM is an IPA?

Most American IPAs sit between about 6 and 14 SRM, running gold to light amber, though hazy versions read lighter and darker variants go further. SRM measures how much light at 430 nanometers the beer absorbs, so it describes depth of color rather than hue. The Brewers Association publishes per-style SRM ranges in its annual style guidelines.

Should I put IBU on my tap list?

Only with a word beside it. The number alone makes servers explain the menu all shift, because customers read a high IBU as harsh when it may be well balanced. Printing "45 IBU, firm but balanced" does the work the bare figure cannot. On your website, keep the number as a labeled field - machines want the value, people want the adjective.

Conclusion: Put the Numbers Where the Search Happens

Fix the website first. The chalkboard is a twenty-minute job you can do next time you rewrite it - drop SRM, keep ABV, turn IBU into a word.

The beer pages are the ones costing you. Give each beer its own URL, put ABV, IBU and SRM in labeled fields rather than buried in a paragraph, add Product schema with additionalProperty for the three specs, and delete the pages for beers you retired two seasons ago. That is the version a search engine can index and an assistant can quote.

Then watch the TTB docket. If Notice No. 237 becomes a final rule, every beer you package will need an alcohol content statement and the tolerance may widen to a full point. Five years is the proposed runway, which sounds like plenty until it is a label redesign across your whole portfolio.

Start with the beer that sells best. If its page cannot answer "how strong is it" in the first sentence, nothing further down the list matters. Working through thirty beer pages by hand is the part nobody has time for, and it is the part BeerSoft picks up. Send the URL of your tap list page and we will tell you what a crawler currently sees on it.

Sources

1. Alcohol and Tobacco Tax and Trade Bureau. Malt Beverage Labeling: Alcohol Content. TTB G 2023-2.
2. Alcohol and Tobacco Tax and Trade Bureau. Alcohol Facts Statements in the Labeling of Wines, Distilled Spirits, and Malt Beverages. Notice No. 237, 90 FR 6654, January 17, 2025.
3. Brewers Association. 2026 Beer Style Guidelines Now Available. January 13, 2026.
4. Brewers Association. Beer Style Guidelines.
5. CraftBeer.com. Beer Styles Study Guide.
6. Electronic Code of Federal Regulations. 27 CFR Part 7 - Labeling and Advertising of Malt Beverages.