Electronic vapor provision system

An electronic vapor provision system including:

• a vaporizer configured to vaporize liquid for inhalation by a user of the electronic vapor provision system;
• a power supply comprising a cell or battery and configured to supply power to the vaporizer;
• a sensor configured to measure the rate of airflow through the electronic vapor provision system as a result of a single inhalation by the user;
• and
• a control unit configured to control the power supplied to the vaporizer for the single inhalation by the user, wherein during each iteration of time within the single inhalation the electronic vapor provision system is adapted to:
• measure the current airflow rate at the sensor;
• update a cumulative airflow by summing the measurements of current airflow rate by the sensor so far during all iterations of time within the single inhalation;
• and
• control, by the control unit, the power supplied to the vaporizer based on the updated cumulative airflow for the most recent iteration of time within the single inhalation and a desired relationship between the cumulative airflow for the single inhalation and amount of vapor output to the user for the single inhalation;
• thereby allowing the user control over the amount of vaporized liquid obtained in an individual single inhalation based on the cumulative airflow for that individual single inhalation.