1 Your electricity rate
Both are on your bill. The unit rate is the price of one kWh. The standing charge is a daily fee you pay whatever you use.
2 Your things
Start from a common one, or add your own. Change the watts and the hours to match yours; the plug label or the maker's page has the real watts.
No things yet. Add one above to see what it costs.
3 What it costs
A year to run
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Two things that quietly change the number
A guide, not a promise. Fridges, heaters and anything with a thermostat switch on and off, so a yearly figure is an estimate. Your real bill also carries tax and any fixed fees.