**The maths behind the calculator**
A mixture of the formulas below and more are used depending on what units you select above. |

The simple calculation is the rate multiplied by the watts (in kW) gives us the cost for one hour. |
cost in pence per hour = Rate x kW |

To use watts instead of kW, we divide the watts by 1000. |
cost in pence per hour = (Watts ÷ 1000) x Rate |

To get the cost for 1 minute, we divide the cost per hour by 60. |
cost in pence per minute = (Watts ÷ 1000) x Rate ÷ 60 |

To get the cost for 1 day, we multiply the cost per hour by 24. |
cost in pence per day = (Watts ÷ 1000) x Rate x 24 |

To get the cost for 1 week, we multiply the cost per hour by 168. |
cost in pence per week = (Watts ÷ 1000) x Rate x 168 |

To make the answer into pounds, we divide the pence by 100 and round it up to two decimal places. |
cost in pounds per hour = (Watts ÷ 1000) x Rate ÷ 100 |

To get the cost in pounds for 1 week, we multiply the cost per hour in pounds by 168. |
cost in pounds per week = (Watts ÷ 1000) x Rate x 168 ÷ 100 |

To get the power in kWh, we take the watts in kW and multiply it by the time in hours. |
power in kWh = kW x time in hours |