Choose the right consumption mode
Use watts and time when you know electrical input and session duration. Use kWh per cycle for washers, dryers and other programme-based products. Daily kWh is useful for a measured 24-hour sample; annual kWh suits energy labels for continuously operating appliances.
Do not enter heat output, cooling BTU/h, battery capacity or microwave cooking output as electrical input. Where a product cycles, run scenarios with a transparent average running percentage. A measurement over a representative period is preferable to an invented duty cycle.
Compare like with like
Keep the service, capacity, time and frequency consistent when comparing two choices. Add both results to the basket or use the comparison tool, which normalises different modes to annual kWh. For a purchase decision, pass the annual figures to the payback tool and include all upfront costs.
Common questions
Frequently asked questions
What information do I need?
Use watts and time, kWh per cycle, kWh per day or annual kWh, plus your pence-per-kWh tariff.
Can I calculate a device not listed on this website?
Yes. Give it a useful label when adding the result to your basket.
Does this predict my electricity bill?
No. It estimates the appliance pattern entered and excludes standing charge and unlisted loads.
How is a month calculated?
The annual total is divided by 12, avoiding the error of treating every month as four weeks.
Where is my result saved?
Only in this browser if you add it to the basket. A share URL contains the non-sensitive assumptions you choose to copy.
Transparent estimates
Results are estimates based on the information entered. Actual energy use can vary by appliance model, settings, temperature, cycling, condition and household behaviour. Review formulas and limitations on the methodology page.
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