Below is a useful calculator widget for calculating various power variables. You don’t need to fill in every field – just fill in what you know and the calculator will give you the remaining variables it can. 

NOTES:

1. UK standard voltage is 230V

2. If you don’t know your power factor, many generator suppliers operate on an assumed PF of 0.8. 

3. Remember to triple your current (Amps) for a three-phase system, i.e. if you are calculating based on a 63-3 supply, your total current will be 189A.