How do I calculate blood alcohol content?

By the Widmark formula: pure alcohol (volume × strength × 0.789) divided by body mass and a distribution factor (men ~0.68, women ~0.55), minus what the liver has eliminated. The calculator does this automatically from your inputs.

How long until alcohol wears off?

The liver eliminates about 0.15‰ per hour. The calculator divides your current BAC by this rate and shows the time to zero. Coffee, a shower or exercise won’t meaningfully speed it up.

Can I drive after the calculation?

Not until the result is zero. The estimate is approximate, and the safe limit for driving is effectively sobriety. Wait for full elimination and don’t risk it.

Why is BAC higher in women for the same dose?

Women’s bodies have less water for alcohol to distribute into, so the concentration for the same dose and weight is higher. This is captured in the distribution factor.

Is the calculator accurate?

It’s an estimate, not a measurement. Real figures depend on food, drinking speed, age and liver health. For a legally meaningful result you need a breathalyser or blood test.

Blood alcohol calculator: BAC and when it wears off

Enter what and how much you drank, your sex and weight — the calculator estimates your blood alcohol content (per mille) using the Widmark formula and shows when it returns to zero. It’s a guide, not a precise measurement: real figures depend on food, elimination rate and your body. Drive only when fully sober.

Estimate BAC and time to sober

Enter volume, strength, sex and weight — the result appears instantly.

What the BAC level means

Approximate effects by blood alcohol content (‰). Varies widely between people; only 0 is acceptable for driving.

BAC, ‰	State
0.0	Sober — safe to drive
0.3–0.5	Mild intoxication
0.5–1.5	Marked intoxication
1.5–2.5	Severe intoxication
over 2.5	Alcohol poisoning

How BAC is calculated (Widmark formula)

Blood alcohol content is estimated with the Widmark formula: the grams of pure alcohol are divided by body mass and a distribution factor (about 0.68 for men, 0.55 for women — women have less body water, so the same dose gives a higher BAC). What the liver has already eliminated is subtracted from the peak.

Pure alcohol is computed from drink volume and strength: e.g. a 500 ml beer at 5% has about 20 g, a 100 ml vodka at 40% about 32 g. Enter your height and the estimate is refined with the Seidl equation.

When alcohol wears off

The liver eliminates alcohol at roughly 0.15‰ per hour (0.10–0.20 across people). The calculator divides your current BAC by this rate and shows how many hours until it reaches zero. You can’t “sleep it off in an hour” or speed it up with coffee, a shower or exercise — the rate is nearly constant.

Why it’s only an estimate

Actual BAC depends on food (which slows absorption), drinking speed, sex, age, liver health and many other factors, so it can differ from a breathalyser. Never drive with any positive result — legally and for safety, only zero is acceptable.

Frequently asked questions

By the Widmark formula: pure alcohol (volume × strength × 0.789) divided by body mass and a distribution factor (men ~0.68, women ~0.55), minus what the liver has eliminated. The calculator does this automatically from your inputs.
The liver eliminates about 0.15‰ per hour. The calculator divides your current BAC by this rate and shows the time to zero. Coffee, a shower or exercise won’t meaningfully speed it up.
Not until the result is zero. The estimate is approximate, and the safe limit for driving is effectively sobriety. Wait for full elimination and don’t risk it.
Women’s bodies have less water for alcohol to distribute into, so the concentration for the same dose and weight is higher. This is captured in the distribution factor.
It’s an estimate, not a measurement. Real figures depend on food, drinking speed, age and liver health. For a legally meaningful result you need a breathalyser or blood test.

Check how alcohol has affected your liver

Upload your liver panel (ALT, AST, GGT) — AI explains the values and what any deviations mean.

Decode my liver test

This calculator is for reference and information only and gives a rough estimate, not a measurement. Drive only when fully sober; only a breathalyser or blood test is legally meaningful.