Electricity cost calculator
Running cost is watts times hours divided by 1,000, multiplied by your price per kWh. A 2,000 W heater for four hours a day at 28p per unit costs £2.24 daily, £68 a month and £818 a year.
How to work out running cost
Two things make the yearly figure the useful one. First, small hourly costs are easy to dismiss and annual ones are not: a 3p-an-hour device left on constantly is £263 a year. Second, it is the right basis for comparing a replacement. An appliance that saves £80 a year justifies a very different purchase price than one that saves £8. Remember that your bill also carries a standing charge that no appliance calculation will ever explain, and that a variable or time-of-use tariff makes the timing matter as much as the total.
Questions
About 56p an hour at 28p per kWh. Four hours a day is £2.24, or over £800 a year.
The one on your bill, including VAT, not the headline advertised rate. They frequently differ.
Individually no, collectively sometimes. A house full of 2 W standby loads is perhaps £30 a year — real but rarely the biggest win.
Per kilowatt-hour, usually three to four times gas. Heat pumps change that arithmetic because they deliver three or four units of heat per unit of electricity.
Standing charges, VAT, and consumption you have not counted. This tool costs one device, not a household.