Introduction: At present, on a lot of public websites “Blood Alcohol Calculator” is available – a method to calculate the elimination of alcohol (calculating time needed for negative breath test) based on Widmark formula. Breathalyzers providing simple measurement of alcohol from the expired air are also readily available. The aim of the study was to compare the results from Widmark formula with a breathalyzer testing. Methods: In a pilot, experimental study performed on general population: N = 30, mean age 40.1 years (SD ± 13.5), 57% males, we (a) calculated the elimination of alcohol according to Widmark, (b) by testing with breathalyzer. Results: All probands reached zero blood alcohol concentration measured by breathalyzer earlier than as it was calculated using Widmark formula. Conclusion: "Blood Alcohol Calculator" - calculation according to Widmark appears to be non-precise, but relatively safe tool to estimate the time of alcohol elimination for drivers, but Widmark formula retrospectively can be used in forensic practice only with caution, since it seems that it overestimates the results.

Key words: Blood Alcohol Calculator – Widmark formula – breath alcohol testing