Your BAC is influenced by whether you are male or female, your body weight and how much alcohol you drink in a given amount of time.
Other factors such as your general health and how quickly your body breaks down alcohol will also affect your BAC.
For example, if you are not in good health or your liver function is poor, your BAC may be higher than shown.
Women and people of both sexes who don't weigh a lot get to higher BACs faster.
This is because they have less blood volume to dilute the alcohol and a lesser capacity to break it down in the same amount of time as someone who is male or heavier.
However, it is only a guide and the safest BAC for driving is zero.