Alcohol Metabolism Calculator
Last updated: 2026-06-25
This calculator uses the Widmark formula and your sex, weight and what you drank to estimate your blood alcohol concentration (BAC) and roughly how long until the alcohol clears.
The result is a reference estimate only and never guarantees a safe time to drive. If you've been drinking, do not drive.
⚠️ Drunk driving is a serious offense and endangers lives. Limits vary by country (often 0.08%, sometimes 0.05% or 0.03%, or zero tolerance). This calculator is not a tool for deciding whether you can drive. If you've been drinking, use a taxi, rideshare or public transit.
Estimate alcohol clearance time from your drinks
Estimated current BAC
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Status: –
- Pure alcohol consumed
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- Peak BAC right after drinking (est.)
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- Until fully cleared (est.)
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- Until at/below 0.03% (est.)
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Please enter a valid weight and amount.
⚠️ This is a simple estimate. Real BAC varies widely with body type, food and condition, and you must never use this result to decide whether to drive. Do not drive after drinking.
How to use it
- Enter sex and weight — select your sex and enter your body weight in kilograms (kg).
- Enter what you drank — choosing a drink auto-fills its ABV; enter total volume (ml) and hours since drinking.
- View result — press Calculate to see your estimated BAC (%) and how long until the alcohol clears.
Alcohol metabolism and the Widmark formula
Blood alcohol concentration (BAC) depends on the pure alcohol you drank, your body weight and your sex, and the liver clears it at a roughly steady rate over time. The most widely used estimate is the Widmark formula.
Widmark formula
Pure alcohol(g) = volume(ml) × ABV(%) ÷ 100 × 0.789 (ethanol density)
BAC(%) = alcohol(g) ÷ (body weight(g) × r) × 100 (r: 0.68 men, 0.55 women)
Clearance: about 0.015% per hour
Drink-drive limits vary by country
| Blood alcohol concentration | Typical significance |
|---|---|
| 0.03% – 0.05% | Over the limit in many strict-limit countries |
| 0.05% – 0.08% | Over the limit in many countries |
| 0.08% and above | Over the limit almost everywhere, severe penalties |
Even one or two drinks can put you over a low limit. Clearance is slower than people think, so after a heavy night you can still be over the limit the next morning (next-day driving).
Remember
- Coffee, cold water and food do not clear alcohol faster. Only time does.
- Clearance varies a lot between people and can take longer than this estimate.
- The safest rule is "if you drink, you don't drive."
- Use a taxi, rideshare, public transit, or wait until well into the next day.
To take care of your health, check the BMI Calculator and Daily Water Intake Calculator.
Frequently asked questions (FAQ)
How many hours after drinking can I drive?
There is no guaranteed safe time. Alcohol clears at different rates for everyone, and this estimate can differ from your real BAC. The safest choice is to not drive at all on a day you've been drinking. You can still be over the limit the next morning.
What is the legal drink-drive limit?
It varies by country and region. Many places set the limit at 0.08% BAC, while others use 0.05% or 0.03% (and some have zero tolerance). Even small amounts can put you over a low limit. This calculator does not guarantee you are under any limit — do not drive after drinking.
How does the Widmark formula work?
The Widmark formula estimates BAC(%) = pure alcohol(g) ÷ (body weight(g) × distribution factor r) × 100, where r is about 0.68 for men and 0.55 for women. Alcohol is then assumed to clear at roughly 0.015% per hour.
Can I trust this result and drive?
Absolutely not. This is a simple average-based estimate that can be far off depending on food, body type, condition and drinking pace. Drunk driving endangers lives. If you've been drinking, use a taxi, rideshare or public transit.
Do coffee or food speed up alcohol clearance?
No. Alcohol clears at a roughly constant rate and is not sped up by coffee, a cold shower, exercise or food. You may feel more alert, but your BAC is unchanged. Only time lowers it.
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Last updated: 2026-06-25