Home Electricity
Electricity Cost Calculator
What an appliance costs to run per hour, day, month and year at your tariff.
cost = watts ÷ 1000 × hours × rate
Also called appliance running cost · cost to run appliance
Energy & Environment · 9 calculators
Home Electricity Calculators
Electricity bills, appliance energy use and running cost, kWh, wattage, standby power and energy savings.
Home Electricity
Appliance Energy Calculator
Yearly energy and cost for the main household appliances, ranked by what costs most.
total = Σ appliance kWh
Also called home appliance energy use · which appliance costs most
Home Electricity
kWh Calculator
Convert watts and hours into kilowatt-hours, or work back from kWh to power or time.
kWh = watts ÷ 1000 × hours
Also called kilowatt hour calculator · watts to kwh
Home Electricity
Wattage Calculator
Power draw from voltage and current, or from energy used over a period.
P = V × I × PF
Also called watts calculator · power draw calculator
Home Electricity
Standby Power Calculator
What devices left on standby cost you each year — the so-called vampire load.
kWh = devices × watts × hours × 365 ÷ 1000
Also called vampire power calculator · phantom load
Home Electricity
Energy Savings Calculator
Savings from an efficiency upgrade, with payback period and lifetime return.
saving = current use × reduction % × rate
Also called efficiency savings calculator · energy upgrade payback
Home Electricity
Appliance Running Cost Calculator
What each household appliance costs to run per use, per month and per year.
cost per use = kWh per use × rate per kWh
Also called cost to run appliance · washing machine running cost
Home Electricity
Battery Backup Calculator
Battery capacity needed to back up your home for a set number of hours.
kWh = load × hours ÷ efficiency ÷ depth o…
Also called home battery size · backup power calculator
Home Electricity
UPS Runtime Calculator
How long a UPS will run your load, from battery capacity, voltage and inverter efficiency.
runtime = Ah × V × DoD × efficiency ÷ load
Also called ups backup time · how long will ups last
Key home electricity formulas
| Electricity Cost | cost = watts ÷ 1000 × hours × rate |
|---|---|
| Appliance Energy | total = Σ appliance kWh · cost = total × rate |
| kWh | kWh = watts ÷ 1000 × hours |
| Wattage | P = V × I × PF · P = kWh × 1000 ÷ hours |
| Standby Power | kWh = devices × watts × hours × 365 ÷ 1000 |
| Energy Savings | saving = current use × reduction % × rate |
| Appliance Running Cost | cost per use = kWh per use × rate per kWh |
| Battery Backup | kWh = load × hours ÷ efficiency ÷ depth of discharge |
| UPS Runtime | runtime = Ah × V × DoD × efficiency ÷ load |
Home Electricity questions
How much does it cost to run a 2 kW heater for an hour?
At 28p per kWh it costs 56p an hour — 2 kW × 1 hour = 2 kWh.