BAC Calculator
Estimate blood alcohol concentration from drinks, body weight and time using the Widmark formula.
Inputs
1 drink ≈ 14 g of pure alcohol
Formula
- BAC = (grams of alcohol / (weight g × r)) × 100 − 0.015 × hours
Widmark's equation spreads the alcohol you drank through the water in your body and subtracts what the liver has cleared (about 0.015% per hour). It is an estimate only: food, medication and individual metabolism shift the real figure a lot.
Step-by-step calculation
- 1
Alcohol mass
drinks × 14 g
42 g
- 2
Widmark
mass / (kg·r) × 100 − 0.015h
0.058%
Warnings
- Never use this to decide whether to drive. Any alcohol impairs driving, and legal limits differ by country.
Frequently asked questions
What does the BAC Calculator do?
Estimate blood alcohol concentration from drinks, body weight and time using the Widmark formula. The BAC Calculator on OneCalcApp returns the result instantly as you type, together with the formula and the substituted values.
How do I use the BAC Calculator?
Enter your values in the input fields, choose the relevant units or options, and the BAC Calculator recalculates automatically. You can copy, print or export the result.
Is the BAC Calculator free to use?
Yes. The BAC Calculator is completely free, needs no sign-up and has no usage limit on OneCalcApp.
How accurate is the BAC Calculator?
It uses the standard formula BAC = (grams of alcohol / (weight g × r)) × 100 − 0.015 × hours and full double-precision arithmetic, so results match a manual calculation to the displayed number of digits.
Does the BAC Calculator work on mobile and offline?
Yes. The BAC Calculator runs entirely in your browser on phones, tablets and desktops, and your inputs never leave your device.
Where can I find related tools?
OneCalcApp hosts 300+ calculators and converters, including the full Health collection. Related tools are linked at the bottom of every page.
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