Blood alcohol estimate
An estimate of your blood alcohol level and how long until it's back to zero. Never a substitute for a breathalyser.
How it works
Widmark formula: alcohol (10 g per standard drink) / (weight × 0.7 for men, 0.6 for women), minus 0.15 g/L per hour. Legal limit in Belgium and France: 0.5 g/L (0.2 for new drivers in France).
Results are for guidance only and do not replace professional advice.
Worked example
With the default values:
- Standard drinks (beer 25 cl, wine 10 cl, spirits 3 cl)3
- Weight (kg)70
- SexMale
- Hours since first drink1
- Have you eaten?No
you get:
- Estimated blood alcohol now0.46 g/L
- Estimated peak0.61 g/L
- Back to 0 g/L in about3 h 05
- Below 0.5 g/L in aboutalready below (estimate)
Frequently asked questions
How does the “Blood alcohol estimate” tool work?
Widmark formula: alcohol (10 g per standard drink) / (weight × 0.7 for men, 0.6 for women), minus 0.15 g/L per hour. Legal limit in Belgium and France: 0.5 g/L (0.2 for new drivers in France).
What do I need to enter?
Just fill in: standard drinks, weight, sex, hours since first drink, have you eaten?. The result updates as you type.
Can you give an example?
Standard drinks (beer 25 cl, wine 10 cl, spirits 3 cl): 3; Weight (kg): 70; Sex: Male; Hours since first drink: 1; Have you eaten?: No → Estimated blood alcohol now: 0.46 g/L; Estimated peak: 0.61 g/L.
Is this calculator free, and is my data private?
Yes. HOD Calc is completely free with no sign-up. The calculation runs in your browser: nothing you type is sent or stored.