For example, a BAC of 0.10 (0.10% or one tenth of one percent) means that there is 0.10 g of alcohol for every 100 mL of blood, which is the same as 21.7 mmol/L . A BAC of 0.0 is sober; in different countries the maximum permitted BAC when driving ranges from about 0.02% to 0.08%; BAC levels over 0.08% are considered ...