Example 1
- Mass: 70 kg
- Ethanol: 14 g
- Sex: male
- Activity: sedentary
2.94 ‰
70 kg, 14 g, male and sedentary gives 2.94 ‰ at r = 0.68.
BAC calculator
Type mass, grams of pure ethanol, and sex. The calculator estimates permille with a Widmark-like formula. Seventy kilograms, 14 g, and a sedentary man give 2.94 permille at r = 0.68. Time since the drink does not enter.
A ‰ sketch from ethanol grams. There is no permission to drive here. Mass category, if you want it, lives on the BMI calculator.
Result
Weight (kg), Pure ethanol (g), Sex and Activity (small r bump). Permille sketch shows up here.
How it works
Permille in this calculator is (ethanol grams / (kilograms times r)) times 10, to two decimals. The factor r starts at 0.68 for a man and 0.55 for a woman. If sex is not chosen, the base is 0.615. Activity adds 0, 0.01, 0.02, 0.03, or 0.04, and r is clamped to 0.50-0.75. Seventy kilograms, fourteen grams, a man, and sedentary mode give 2.94 permille at r = 0.68, because 14 / 47.6 times 10.
People look up an online breathalyzer because they want to know whether they may drive. This page does not decide that. It does not know minutes since the drink, an empty stomach, or the liver. It does not convert beer, wine, or spirits into grams: you type ethanol yourself. One standard beer is often around 14 g, but brands and glasses differ. The ‰ result is not US blood-alcohol percent. 0.08% there is a different scale.
The same 70 kg and the same sedentary man at 20 g give 4.20 permille. Sixty kilograms, 10 g, and a sedentary woman is 3.03 permille at r = 0.55. Ninety kilograms and 14 g in a sedentary man drops to 2.29 permille, because mass is in the denominator. Fifty-five kilograms, 20 g, and a sedentary woman is 6.61 permille. A large number from a small mass, still a paper sketch, not a tube.
Activity is a small, subjective tweak to r, not a liver-burn model. Moderate mode at 80 kg and 20 g in a man lifts r to 0.70 and gives 3.57 permille. Light activity at 75 kg and 10 g is r = 0.69 and 1.93 permille. A 65 kg woman, 14 g, and moderate mode is r = 0.57 and 3.78 permille. The US switch converts pounds with 0.453592, then runs the same math in kilograms.
A police officer, a roadside breathalyzer, and a blood test govern the road. This calculator is for learning units in class. If you are not sure, you do not drive. Sleep cycles next door do not subtract permille for a bad night, and daily water does not dilute the formula.
Type 70, 14, and a sedentary man, then Calculate. You should see 2.94 permille and r = 0.68. Then change 14 to 20 and watch 4.20. Treat both numbers as a paper exercise, not as permission to take the keys. Blood alcohol uses the Widmark formula.
How to use
- Type body mass in kilograms or pounds, matching the units switch.
- Type grams of pure ethanol, not milliliters of beer, wine, or spirits. The calculator does not convert drinks.
- Pick sex and activity. Activity only nudges r a little. Then click Calculate.
- Read permille to two decimals and r. At 70 kg, 14 g, and a sedentary man you get 2.94 permille and r = 0.68.
- Time since the drink and a drive time do not enter. If you are not sure, you do not drive.
Formula
permille = (g ethanol / (kg × r)) × 10
r = sex base (male 0.68, female 0.55, else 0.615) plus activity 0 / 0.01 / 0.02 / 0.03 / 0.04, clamped to 0.50-0.75. Output is ‰, not BAC%. Not a breathalyzer.
Permille, Widmark r, and ethanol grams
The ‰ sketch is (g ethanol / (kg × r)) × 10. 70 kg, 14 g, and a sedentary man give 2.94 permille at r = 0.68. Time since the drink does not enter.
- Widmark
- A family of formulas with an r factor and ethanol grams. Here (14 / (70 × 0.68)) × 10 = 2.94 permille. A paper sketch, not a breathalyzer.
- ethanol
- Grams of pure ethanol from the field, not milliliters of beer. 14 g at 70 kg and r = 0.68 is 2.94; 20 g at the same numbers is 4.20.
- permille
- The ‰ unit in this calculator, not US BAC percent. 2.94 permille from the 70/14/male example is not 0.294% and does not divide by ten by a rough estimate.
- BAC
- Blood alcohol concentration in percent, a different scale. The calculator result is ‰. BAC 0.08% is not the same as 2.94 permille from the example.
- r
- The distribution factor: 0.68 male, 0.55 female, plus a small activity nudge, clamped to 0.50-0.75. A sedentary man stays at 0.68.
Examples
Example 2
- Mass: 70 kg
- Ethanol: 20 g
- Sex: male
- Activity: sedentary
4.20 ‰
The same 70 kg and male, but 20 g ethanol, gives 4.20 ‰.
Example 3
- Mass: 60 kg
- Ethanol: 10 g
- Sex: female
- Activity: sedentary
3.03 ‰
60 kg, 10 g, and a sedentary woman gives 3.03 ‰ at r = 0.55.
Example 4
- Mass: 80 kg
- Ethanol: 20 g
- Sex: male
- Activity: moderate
3.57 ‰
80 kg, 20 g, male and moderate activity gives 3.57 ‰ at r = 0.70.
Example 5
- Mass: 90 kg
- Ethanol: 14 g
- Sex: male
- Activity: sedentary
2.29 ‰
90 kg and 14 g for a sedentary man gives 2.29 ‰, lower than at 70 kg.
Example 6
- Mass: 55 kg
- Ethanol: 20 g
- Sex: female
- Activity: sedentary
6.61 ‰
55 kg, 20 g, and a sedentary woman gives 6.61 ‰. Still not a breathalyzer.
Example 7
- Mass: 75 kg
- Ethanol: 10 g
- Sex: male
- Activity: light
1.93 ‰
75 kg, 10 g, male and light activity gives 1.93 ‰ at r = 0.69.
Example 8
- Mass: 65 kg
- Ethanol: 14 g
- Sex: female
- Activity: moderate
3.78 ‰
65 kg, 14 g, female and moderate activity gives 3.78 ‰ at r = 0.57.
Frequently asked questions
Does this calculator replace a breathalyzer?
No. It computes permille from ethanol grams and mass. A breathalyzer measures air. This page does not know when you may drive.
Why do 70 kg, 14 g, and a sedentary man give 2.94 permille?
Because (14 / (70 × 0.68)) × 10. Time since the drink does not enter. The result is a Widmark sketch, not a blood reading.
Is ‰ the same as US BAC percent?
No. Here you have permille. BAC 0.08% is a different unit. Law and labs use their own scales. Do not divide by ten by a rough estimate.
How do I enter beer if the field wants grams?
Convert ethanol yourself. The page has no beer table. One standard drink is often about 14 g, but brands and glasses differ.
Why activity if this is not liver metabolism?
It is a small tweak to r, from zero to 0.04. Moderate mode at 80 kg and 20 g in a man lifts r to 0.70 and gives 3.57 permille.
When may I drive after 1.93 permille in the 75 kg example?
This page does not say. 1.93 permille is a sketch from 10 g of ethanol. If you are not sure, you do not drive.
Do pounds in US mode change 2.94 permille at the same kilograms?
No, if you convert 70 kg with 0.453592 and type that mass. A different pound mass gives a different result.
Does a 60 kg woman with 10 g always sit above a 70 kg man with 14 g?
In the examples, 3.03 permille versus 2.94, because her r is 0.55. Another mass and gram pair can flip the order.
Does time since the drink lower 4.20 permille at 20 g?
Not in this calculator. The formula does not know minutes. You see a level from grams and mass, with no decay curve.
What do I get at 90 kg, 14 g, and a sedentary man?
2.29 permille, lower than at 70 kg, because mass is in the denominator. 55 kg, 20 g, and a sedentary woman is 6.61 permille.
Knowledge sources
A ‰ sketch from ethanol grams and mass. This is not permission to drive.
Page updated in 2026.