"How many units is that pint?" is a question we get asked constantly on our guided tours, usually somewhere around taproom three, when someone's doing mental maths against their weekly total. The honest answer is: it depends entirely on strength, and most people underestimate it by a fair margin — especially with modern craft beer, which tends to run stronger than the lager most of us grew up on. Here's the maths properly explained, a quick-reference table for common strengths, the official UK guidelines, and how we think about pacing a full day of tasting on the Bermondsey Beer Mile.
The unit formula, in plain English
In the UK, one alcohol unit is defined as 10ml (or 8g) of pure ethanol. Every drink's unit count depends on two things: how much liquid you're drinking, and how strong it is (its ABV, or alcohol by volume). The formula is:
units = (volume in ml × ABV%) ÷ 1,000
A UK pint is 568ml, so for a full pint you can simplify the sum to roughly ABV% × 0.568. So a 4.5% pale ale pint is 4.5 × 0.568 ≈ 2.6 units. A 6.8% double IPA pint is 6.8 × 0.568 ≈ 3.9 units. It's a bigger jump than most people expect between what looks like "one beer" and the next.
Units in a pint, by strength: quick-reference table
Here's the maths done for you across the strengths you'll actually meet on a taproom crawl, from a session lager to a big imperial stout.
| Beer style (typical ABV) | Units in a pint (568ml) |
|---|---|
| Session pale / session IPA (3.5%) | ≈ 2.0 units |
| Standard lager (4%) | ≈ 2.3 units |
| Cask ale / bitter (4.2%) | ≈ 2.4 units |
| Craft lager / pale ale (4.5–5%) | ≈ 2.6–2.8 units |
| Standard IPA (5.5–6%) | ≈ 3.1–3.4 units |
| Double / imperial IPA (7.5–8.5%) | ≈ 4.3–4.8 units |
| Imperial stout (9%+) | 5+ units |
Notice how quickly it climbs. A pint of a 9% imperial stout can contain more than double the units of a session pale ale — worth remembering if you're sampling several different styles in an afternoon, which is exactly what happens on a guided Beer Mile tour.
Two-thirds and halves: the maths for smaller measures
Most London taprooms, including all six on our tour, pour in two-thirds (379ml) and halves (284ml) as well as full pints, and it's genuinely the smarter way to taste widely. Using the same formula: a two-thirds of a 6% IPA is 6 × 0.379 ≈ 2.3 units — the same as a full pint of standard lager. A half of that same IPA is roughly 1.7 units. If you want to try six different styles across a day, smaller measures let you do that without stacking up a huge unit count in one sitting.
What the UK guidelines actually say
The UK Chief Medical Officers' guidelines recommend no more than 14 units a week for both men and women, spread across three or more days, with several drink-free days included. Fourteen units works out to roughly six pints of standard-strength (4%) lager, or fewer if you're drinking stronger craft beer — closer to four or five pints of a 6% IPA. These are described as "low risk" guidelines, not a target, and if you regularly drink above this it's worth reading the NHS and Drinkaware guidance on cutting down.
Why craft beer changes the sums
A generation ago, "a beer" reliably meant something around 3.5–4.2% ABV. Modern craft brewing has widened that range enormously: session beers can be lower, hazy IPAs and double IPAs routinely sit at 6–9%, and specialist releases (barrel-aged stouts, triple IPAs) can run past 10%. That's brilliant for flavour and variety, but it does mean the old mental shortcut of "a pint is about two units" is now often wrong — sometimes by double. Always check the ABV on the pump clip or can, which UK breweries are required to display.
It's also worth knowing that ABV isn't fixed by style — it's a range. Two beers both labelled "IPA" might be 4.8% and 8.2% respectively, with wildly different unit counts per pint despite looking near-identical in the glass. Cask ales and classic bitters tend to sit at the lower end (3.5–4.5%), keg lagers cluster around 4–5%, and the newer wave of hazy, hop-forward styles is where you'll find the biggest strengths. If you're working through several taprooms in an afternoon, glancing at the ABV on each pump clip before you order takes seconds and keeps your running total realistic.
A note on driving, pregnancy and other zero-tolerance situations
Unit counting is about weekly guidelines, but it's a different question entirely if you're driving, cycling somewhere that requires full concentration, or pregnant. The safest position on all three is well below any "guideline" maths — the NHS advice for pregnancy is to avoid alcohol entirely, and the only truly safe amount before driving is none. None of the sums in this article are a substitute for that kind of judgement call; they're for working out your weekly total on an ordinary day out.
How we think about pacing on a tasting day
Our guided Beer Mile Tour (£49pp, 2–3.5 hours, tastings included) visits four taprooms across an afternoon, and we've been doing this since 2014 — so pacing is something our guides talk about constantly. A few practical habits:
- Ask for thirds or halves at the stronger stops. It's not "not drinking properly" — it's how you taste more styles without overdoing the units.
- Check the ABV before you order. A 4% pale and an 8% double IPA look identical in the glass but are worlds apart in strength.
- Eat before and during. Food slows absorption and makes for a much better afternoon regardless of your unit count.
- Drink water between stops. Especially on a warm day walking the arches between taprooms.
- Track roughly as you go. A running mental tally — even a loose one — helps you decide whether that last stop is a full pint or a half.
If you'd like a lighter add-on to the day, our heritage walk in the morning is a great way to build in a beer-free stretch, and our Saturday cheese, meat & beer tour is a smaller, seated tasting rather than pint-for-pint drinking.
Units aren't the only measure that matters
Units tell you about alcohol content, not about your overall wellbeing on the day — hydration, food, sleep and how you're feeling all matter just as much. If you're curious how ABV relates to what's actually going on in the glass, our guide to how beer is made explains where strength comes from during fermentation, and our beginner's guide to beer tasting has more on tasting technique that naturally slows you down and helps you drink more mindfully.
Planning a group day out?
Unit awareness matters even more in a group setting, where rounds and peer pace can push people to drink faster than they'd choose alone. Our guides actively manage pacing across the group, and it's one of the reasons private tours for birthdays, stag and hen groups and work socials tend to go so much more smoothly guided than unguided. See our London pub crawl routes piece if you're planning something yourself and want more tips on keeping a group's pace sensible.
A gift that comes with built-in pacing
If you're buying for a beer lover, a guided tasting day is a thoughtful way to introduce them to stronger, more varied craft styles without the "how many units was that" anxiety of drinking unguided — our guide handles the pacing and the tasting notes. Gift vouchers are delivered instantly by email and never expire.