BAC Calculator · Practical guide
What Is My BAC After 3 Beers?
Three standard beers affect a 120-pound woman and a 220-pound man very differently — here are the numbers.
At a glance
The Short Answer
Three standard beers (12 oz at 5% each) in about an hour put a 180-pound man near 0.061% BAC and a 150-pound woman near 0.097% — the latter above the 0.08% legal limit in every US state. Weight and gender swing the estimate more than most people expect, which is why the calculator above asks for both.
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Enter your own values, then compare the result with the examples below.
One standard drink contains approximately 14 grams of pure alcohol.
Alcohol Metabolism Estimate
Estimated BAC After 3 Beers in One Hour
| Person | Estimated BAC | Vs. 0.08% Legal Limit |
|---|---|---|
| 120 lb woman | 0.125% | Over |
| 150 lb woman | 0.097% | Over |
| 150 lb man | 0.076% | Just under |
| 180 lb man | 0.061% | Under |
| 220 lb man | 0.047% | Under |
Why the Spread Is So Wide
The Widmark formula divides the alcohol consumed — 3 × 14 = 42 grams — by your body water, which scales with weight and is proportionally higher in men (factor 0.68) than women (0.55). Double the body weight and you roughly halve the BAC from the same drinks. Then subtract 0.015% for each hour since the first drink: those same 3 beers spread over 3 hours leave a 180-pound man near 0.031% instead of 0.061%.
What Counts as One Beer
These numbers assume standard drinks: 12 oz at 5%. A 16-oz pint of 7% IPA is about 1.9 standard drinks, so three of those behave like nearly six standard beers — enough to put even a 220-pound man over 0.09% in an hour. Count honestly, and when the estimate is anywhere near 0.08%, do not drive.
Frequently Asked Questions
Is 0.061% safe to drive at?
It is below the 0.08% legal limit for drivers 21+, but impairment begins well under that threshold, and some states can cite you at lower levels. Under-21 drivers face zero-tolerance laws.
How long until 3 beers leave my system?
From a 0.061% peak, about 4 hours to reach zero at the standard 0.015% per hour burn rate. From a 0.097% peak, closer to 6.5 hours.
Do light beers count less?
Most light beers are 4.2% alcohol versus 5% for regular, so each is roughly 0.84 of a standard drink — a modest reduction, not a free pass.
Why do women reach higher BAC from the same drinks?
On average women have proportionally less body water to dilute alcohol (Widmark factor 0.55 vs 0.68 for men), so the same number of drinks at the same weight produces a higher BAC.