🍺Blood Alcohol Calculator

BAC Calculator — how does the Widmark formula work?

The Widmark formula is an established method for estimating blood alcohol concentration (BAC). The calculator computes the total grams of pure ethanol from all entered drinks (volume x alcohol content x 0.789), then divides by the product of body weight and the distribution factor (0.7 for men, 0.6 for women). The elimination constant beta = 0.15 per mille is subtracted for each full hour since consumption. Any result below zero is treated as 0 per mille. The result is indicative only and does not authorise driving a vehicle.

BAC and the law — legal limits

Legal BAC limits vary by country. Always check the local rules. The calculator uses the Widmark estimate — actual breathalyser or blood test results may differ due to individual metabolism, food intake, medication, and other factors. Never drive after consuming alcohol — no calculator result can guarantee your actual sobriety.

Frequently asked questions

How is blood alcohol content calculated?

The calculator uses the Widmark formula: BAC (per mille) = grams of alcohol / (body weight x r) - beta x t, where r = 0.7 for men and 0.6 for women, and beta = 0.15 per mille/h is the elimination constant. The result is indicative — alcohol metabolism depends on many individual factors.

What are the legal BAC limits for driving?

Legal limits vary by country. In Poland, the limit is 0.2 per mille (impairment) and above 0.5 per mille constitutes a criminal offence. In many EU countries the limit is 0.5 per mille; in some it is 0.2 or even 0.0 per mille. Always check the rules of the country you are in.

Can I drive if the calculator shows 0.0 per mille?

No. The calculator result is indicative only and must not be used as a basis for deciding to drive. The actual blood alcohol level depends on individual metabolism, health status, food intake, and other factors. The only reliable measurement method is a breathalyser or blood test.

How many grams of alcohol are in beer, wine, and spirits?

For example: 500 ml beer at 5% contains about 19.7 g of pure alcohol; 150 ml glass of wine at 12% — about 14.2 g; 50 ml shot of vodka at 40% — about 15.8 g. The calculator automatically converts grams of alcohol for each drink entered, using ethanol density of 0.789 g/ml.