Alcohol Clearance Calculator
Estimate your blood-alcohol level and how long until it returns to zero, using the Widmark equation — and see why those drinks cost you a night of recovery.
⚠ Educational estimate only, with large individual variation. This is not a tool for deciding whether it is safe or legal to drive. If you have been drinking, do not drive.
Peak BAC ≈ 0.082%
One standard drink = 14 g pure alcohol (≈ 350 ml beer at 5%, 150 ml wine at 12%, or 45 ml spirits at 40%). Elimination is assumed at 0.015% per hour. Real clearance varies with genetics, food, medication and liver health. The 0.05% line is a common — not universal — legal limit; many places are lower or zero. Never drive after drinking.
See the recovery cost in your data
Alcohol suppresses REM and tanks overnight HRV. ONDA Life tracks how your sleep and recovery respond to drinking — so you can see the real trade-off, not just the hangover.
Download ONDA Life on the App Store →Common questions
How long does it take to sober up?
Your body clears alcohol at a roughly fixed rate — about 0.015% BAC per hour, or close to one standard drink per hour — regardless of coffee, cold showers or food. So four drinks can take five to six hours or more to fully clear. Nothing reliably speeds this up; only time lowers your BAC.
How is blood alcohol content (BAC) estimated?
This tool uses the Widmark equation: it divides the grams of pure alcohol consumed by your bodyweight and a distribution ratio (about 0.68 for men, 0.55 for women), then subtracts the alcohol eliminated since your first drink. One standard drink is treated as 14 g of pure alcohol.
Is this accurate enough to decide if I can drive?
No. This is an educational population estimate with large individual variation — genetics, food, medication, liver health and drink strength all shift the real number. Never use it to decide whether it is safe or legal to drive. If you have been drinking, do not drive; arrange another way home.
Why does alcohol wreck my sleep?
Alcohol helps you fall asleep but fragments the second half of the night: it suppresses REM sleep, increases awakenings and lowers heart-rate variability (HRV) as your body metabolises it. That is why even a few drinks can leave you feeling unrested and show up as poor recovery on a wearable the next morning.
Does body size and sex change how alcohol affects me?
Yes. The same number of drinks produces a higher BAC in a smaller person, because the alcohol is distributed through less body water. Women tend to reach a higher BAC than men of the same weight because of differences in body-water proportion, which is why the formula uses a lower distribution ratio for women.