Indicative blood alcohol estimate (Widmark formula)
Enter what you drank, your weight, your sex and the time since the first drink. The tool gives a very rough range. It never says whether you can drive: the only safe level for driving is zero alcohol.
General information, not medical advice. This result does not replace a doctor. If in doubt or if you have symptoms, see a health professional.
Result
0.18 – 0.36Estimated range (g/L of blood)
- This result is never a permission to drive. The only safe level for driving is zero alcohol: if you have been drinking, do not drive.
- Central value (g/L)
- 0.26
- Theoretical peak with no elimination (g/L)
- 0.41
- Pure alcohol drunk (g)
- 19.7
- Even an estimate of 0 does not prove that alcohol has left your blood: only a real measurement can tell, and the effects can last longer.
Inputs
- Number of identical drinks
- 2
- Volume of one drink
- 250
- Alcohol strength
- 5
- Time since the first drink
- 1
- Weight
- 70
- Sex (for the formula)
- Man
How it is calculated
Pure alcohol (g) = drinks × volume (mL) × strength ÷ 100 × 0.789.
Result
Estimated range (g/L of blood)
- Central value (g/L)
- 0.26
- Theoretical peak with no elimination (g/L)
- 0.41
- Pure alcohol drunk (g)
- 19.7
How it is calculated
- Pure alcohol (g) = drinks × volume (mL) × strength ÷ 100 × 0.789.
- Widmark formula: level (g/L) = alcohol ÷ (r × weight) − β × hours; r = 0.68 for a man, 0.55 for a woman; β = 0.15 g/L per hour as the central value.
- Range: r ± 10% and β from 0.10 to 0.20 g/L per hour. The result never goes below 0.
Example
2 drinks of 250 mL at 5%, man of 70 kg, 1 h after the first drink: 19.7 g of alcohol; range 0.18 – 0.36 g/L; central value 0.26 g/L; theoretical peak 0.41 g/L.
Good to know
- A very rough population estimate: food, medicines, tiredness, liver health and drinking speed change the real level a lot.
- Never replaces a breath test or a blood test, and never says when you will be able to drive.
- If someone feels unwell after drinking, call 112 (or 911 in North America).
Sources
- Widmark E.M.P., Die theoretischen Grundlagen und die praktische Verwendbarkeit der gerichtlich-medizinischen Alkoholbestimmung, 1932
- Jones A.W., Evidence-based survey of the elimination rates of ethanol from blood, Forensic Science International, 2010
Frequently asked questions
What is this tool used for?
Enter what you drank, your weight, your sex and the time since the first drink. The tool gives a very rough range. It never says whether you can drive: the only safe level for driving is zero alcohol.
How is the result calculated?
Pure alcohol (g) = drinks × volume (mL) × strength ÷ 100 × 0.789.
What should I check before using the result?
A very rough population estimate: food, medicines, tiredness, liver health and drinking speed change the real level a lot.