The Drinkdriving.org BAC calculator is a FREE and easy to use, yet comprehensive, BAC calculator. It provides a very accurate estimation of an individuals blood alcohol content at a given point in time based on age, gender, weight, the amount of time since the first drink and the quantity and strength of alcohol consumed. The calculations are based on the widmark method. Users can select from predefined drink measures and enter their own drink strength percentage or they can enter their own measures in ml, fl oz, litres or cl. Unlike other BAC calculators this calculator takes into account several factors that could affect BAC and also allows for multiple drinks to be added before the BAC calculation is carried out.