Loading page
About this tool
Count standard alcohol units from real drink sizes, track your week, and estimate blood alcohol with the Widmark formula.
The Alcohol Units & BAC Calculator counts UK units from the real volume and ABV of what you drank using units = ml × ABV% ÷ 1000, then estimates blood alcohol with the Widmark formula: BAC% = (grams of alcohol × 100) ÷ (body weight in grams × r) − 0.015 × hours since the first drink. It converts the same session into US standard drinks (14 g of pure alcohol each), tracks a rolling seven days against the 14-unit low-risk guidance, and shows how long the estimate takes to fall back to zero. Everything is an informational estimate from population averages — it is not a measurement, and never a basis for deciding whether to drive.
Open Alcohol Units & BAC Calculator on AltFTool — it loads instantly in your browser.
In What have you had?, press the + button on any of the 14 drink rows - Beer at 330 ml and 5%, Wine at 150 ml and 12%, Large peg at 60 ml and 42.8% and eleven more - or type a Volume (ml) and ABV (%) under Something else? and press Add.
Read the Session total panel: UK units calculated as ml × ABV% ÷ 1000, alongside US drinks, grams of alcohol and calories, with minus, plus and bin buttons on each line and Clear to empty the session.
Fill in Body weight (kg), Body-water factor and Hours since your first drink to get the Widmark BAC estimate with Back to 0.00%, Below 0.05% and Below 0.03% (India) timings. Food in your stomach changes only the absorption-context note, not the calculated BAC; then press Save to my week or Copy.
A 30 ml peg at 42.8%, a 568 ml pint at 5% and a 750 ml bottle of wine are each counted on their own numbers.
The r value, your weight in grams and the elimination subtraction are all printed, so the estimate can be checked rather than trusted blindly.
It refuses to pretend food shortens your time to sober, and states plainly that a low reading is not evidence you are under any legal limit.
Units = volume in ml × ABV% ÷ 1000. A 330 ml beer at 5% is 1.65 units, a 175 ml glass of wine at 12% is 2.1 units, and a 750 ml bottle of wine at 12% is 9 units. One UK unit is 10 ml — about 8 g — of pure alcohol.
UK Chief Medical Officers' guidance is no more than 14 units a week, spread over three or more days, with several drink-free days. Guidance differs between countries, and 14 units is described as a low-risk line rather than a safe one — no level of drinking is completely risk-free. Speak to a doctor about your own drinking rather than relying on a threshold.
Roughly 0.015% BAC per hour for most adults, which works out to about one unit an hour. A reading of 0.06% therefore takes around four hours to reach zero. Coffee, a cold shower, food and sleep do not speed elimination up — only time does. This is an average rate, and individual clearance varies.
No. This is arithmetic on population averages, not a measurement of you, and two people of the same weight and sex drinking identically can land at meaningfully different real readings. India's legal limit is 0.03% BAC — 30 mg per 100 ml of blood — and driving at or above it is a criminal offence under the Motor Vehicles Act. If you have been drinking, do not drive.
Add the Alcohol Units & BAC Calculator widget to your blog or website — free, responsive, no signup. Just keep the “Widget by AltFTool” credit link visible.
<iframe src="https://www.altftool.com/embed/widget/alcohol-unit-calculator"
title="Alcohol Units & BAC Calculator — free AltFTool widget"
width="100%" height="640" style="border:0;border-radius:12px;overflow:hidden"
loading="lazy" referrerpolicy="no-referrer-when-downgrade" allow="clipboard-write"></iframe>
<p style="font-size:12px;margin:4px 0 0">Widget by <a href="https://www.altftool.com/tools/all/alcohol-unit-calculator?utm_source=embed&utm_medium=widget" rel="nofollow">AltFTool — free online tools</a></p>