Blood Alcohol Calculator – Calculate Blood Alcohol Level Online Free
Use our free blood alcohol calculator to estimate your BAC. Remember: this is only an estimate – never drive after drinking alcohol.
Calculate your blood alcohol level
1 unit = 33 cl beer (4.5%), 1 glass of wine (12%), 4 cl spirits (40%)
Enter gender, weight and number of units to calculate blood alcohol level
Important disclaimer
This is only an estimate based on the Widmark formula. Actual blood alcohol level is affected by many factors such as food intake, medication, individual differences and drinking speed. Never drive after drinking alcohol, regardless of what the calculator shows. Norwegian law sets the blood alcohol limit for driving at 0.2‰.
How the blood alcohol calculation works
The calculator uses the recognised Widmark formula to estimate blood alcohol concentration. The formula takes into account gender, weight, amount of alcohol and time since you started drinking.
Male (r = 0.7)
Men generally have more body fluid relative to weight, which gives a lower blood alcohol level per unit.
Female (r = 0.6)
Women have less body fluid relatively, and reach a higher blood alcohol level from the same amount of alcohol.
Breakdown
The body breaks down approx. 0.15‰ per hour. Food and coffee do not significantly affect this rate.
One unit
Equals 10 grams of pure alcohol. That's approx. 33 cl beer, one glass of wine or 4 cl spirits.
Norwegian blood alcohol limits
Tips to keep your blood alcohol level low
Drink water in between
One glass of water between each drink effectively halves the rise in blood alcohol over the evening.
Eat well
A solid meal before and during drinking considerably slows the absorption of alcohol into the blood.
Drink slowly
The body can handle one unit per hour. If you drink slower than this, your blood alcohol level will never rise much.
Frequently asked questions about the blood alcohol calculator
How does the calculator work?
The calculator uses the Widmark formula and takes into account gender, body weight, number of drinking units and time since the first drink to estimate blood alcohol concentration (BAC). Men have a distribution coefficient (r) of 0.7 and women 0.6, which reflects differences in body fluid proportion.
Is the calculator accurate?
It is an estimate based on the standard formula. Actual blood alcohol level is affected by individual factors such as metabolism, food intake, medication and general health. The calculator should never be used as the basis for a decision to drive – never drive after drinking alcohol.
What is the blood alcohol limit for driving in Norway?
In Norway, the legal blood alcohol limit for driving is 0.2‰ – one of the strictest in the world. Even at low blood alcohol levels, reaction time is prolonged and judgement is impaired. Always use a taxi, public transport or a sober driver after an evening with alcohol.
How long does alcohol stay in the body?
The body breaks down alcohol at a fixed rate of approx. 0.15‰ per hour, regardless of coffee, food or fresh air. A blood alcohol level of 1.0‰ therefore takes approximately 6–8 hours to burn off completely. The calculator shows the estimated time to 0‰ based on your current blood alcohol level.
What counts as one alcohol unit in Norway?
In Norway, 1 alcohol unit equals 15 grams of pure alcohol. In practice that is approximately: 0.33 litres of beer (4.7%), 0.15 litres of wine (13%), or 4 cl spirits (40%). Strong craft beers and cocktails can contain 2–3 units per glass.
Always drink responsibly
Read our guide on responsible drinking for more tips on having fun in a safe and conscious way.
Read about responsible drinking →