Electricity running cost calculator
Most load calculations end with a question about cost rather than capacity. Enter the wattage, the hours, and your rate.
Check a recent bill — the all-in rate including delivery is usually higher than the advertised supply rate.
Use your all-in rate, not the supply rate
Bills usually separate supply from delivery, and people plug in only the supply figure — which understates the true cost, often substantially. Divide the total bill by the kWh consumed to get what you actually pay per unit.
If you're on a time-of-use tariff, the number that matters is the rate during the hours the device actually runs. A pool pump on a timer overnight costs very different money from one running through the afternoon peak.
Nameplate wattage overstates most things
A nameplate figure is maximum draw, not average. Anything thermostatically controlled — fridges, heaters, air conditioning, water heaters — cycles on and off, so actual consumption is well below nameplate times hours.
For those, a plug-in energy monitor over a week gives a far more honest answer than any calculation. Use the calculation for continuously running loads, where nameplate is close to reality.
Questions
How do I find the wattage?
The nameplate or rating label, usually on the back or underneath. If it lists only amps and volts, multiply them — and use the watts–amps–volts calculator if there's a power factor to account for.
What's a typical electricity rate?
It varies enormously by region, and the all-in delivered rate is what matters. Rather than using an average, divide your last bill total by the kWh it covered.