How it is calculated
The distribution factor is 0,7 for a man and 0,6 for a woman. Alcohol is volume × strength × 0,789 g/mL. The fall is taken as 0,15 g/L per hour. Do not use this figure to decide whether to drive.
g/L ≈ alcohol / (weight × r) − 0,15 × hours
Where the numbers come from
- Sex
- Weight — unit in the field: kg
- Drink volume — unit in the field: mL
- ABV — unit in the field: %
- Hours elapsed — unit in the field: h
Example
A man of 80 kg, 500 mL of a 5% drink, and zero hours. About 19,7 g of alcohol, and an estimate near 0,35 g/L.
Questions
Is this a breathalyzer?
No. The formula does not know your metabolism, your food, or how fast you drink.
Is 0,3 g/L a limit for the road?
The legal threshold is defined differently, and it is measured with an instrument. The screen only shows when the estimate would have fallen to 0,3 under a steady decline.
Several drinks?
Add up the pure alcohol yourself, or work out the volume of one average drink. There is no separate line for each drink.