Electricity Cost Calculator
Whether you are pricing a workshop, a server room or a single appliance, the maths is the same: energy (kWh) equals power (kW) times time (hours), and cost equals energy times your tariff. Enter the load, how long it runs, and your rate per kWh to get daily, monthly and yearly figures.
Formulas: Energy (kWh) = watts ÷ 1000 × hours · Cost = energy × rate
Worked example: a 1500 W heater running 8 hours a day at 0.15 per kWh: 1.5 × 8 = 12 kWh per day, costing 1.80 per day, about 54 per month and 657 per year. That yearly figure is why a slightly more efficient appliance often pays for itself — and why the three-phase power calculator is worth running before sizing a big load.
Tariffs with demand charges, time-of-use rates or tiered pricing will differ from this flat-rate estimate — use your bill's average rate per kWh for the closest real-world comparison.
Frequently asked questions
What is a kWh?
One kilowatt-hour is one kilowatt of power used for one hour — a 1000 W appliance running for one hour uses 1 kWh. Your electricity bill charges per kWh.
Why is my bill higher than this calculator says?
Bills often add fixed daily charges, demand charges, taxes and tiered or time-of-use rates. This calculator estimates the energy portion only, at a single flat rate.
How do I cut the cost of a big load?
Reduce the watts (more efficient equipment), reduce the hours (controls, timers, automation), or shift use to cheaper off-peak hours if your tariff allows it.