Guides
Longer reads on the questions the calculator cannot answer in one number.
2026-10-23BAC Chart by Weight and Number of DrinksA BAC chart worked out from the Widmark formula: estimated blood alcohol in per mille and percent for men and women from 50 to 110 kg after one to six drinks — and why a chart can only ever be a rough guide.Read the guide →2026-10-23Can You Still Be Over the Limit the Next Morning?Why a night's sleep does not reset your blood alcohol, how to work out when you will really be at zero, and the figures for common evenings — computed, not guessed.Read the guide →2026-10-23How Breathalyzers Work – Breath vs Blood AlcoholHow a breathalyzer turns the alcohol in your breath into a blood alcohol figure, why every country uses its own conversion, and why a home tester is not a green light.Read the guide →2026-10-23Zero Tolerance for New Drivers – Country by CountryWhich countries set a lower or zero alcohol limit for new drivers, drivers under 21 and professional drivers, each read off the government source, with what it means in practice.Read the guide →2026-10-23The Widmark Formula Explained, With Worked ExamplesThe Widmark formula behind every BAC calculator, explained term by term with worked examples, the Watson refinement, and the limits of what any formula can tell you.Read the guide →