ToolStaxx guide
How to calculate electricity running cost
Running cost comes from power use, time and the unit price you pay per kWh.
Quick answer
Running cost comes from power use, time and the unit price you pay per kWh.
How to do it
- Convert watts to kilowatts by dividing by 1000.
- Multiply kW by hours to get kWh.
- Multiply kWh by your unit price.
- Real cost changes with tariffs, standby use and duty cycle.
Worked example
1000 W for 4 hours a day over 30 days is 120 kWh. At 28p/kWh, cost is £33.60.
Common mistakes
- Assuming an appliance runs at full power constantly.
- Using the wrong tariff/unit price.
- Forgetting standby or duty-cycle behaviour.
When this is not suitable
Do not treat any quick estimate as a final specification where safety, contracts, regulations or expensive purchases depend on it.
Related next tools
Next useful tools for this task.
Keep the result together
Use the calculator first, then add the result to a Project Sheet if you need a clean printable summary.
Open Project Sheet Builder