What is a kWh?
Confused by kWh on your bill? Learn what a kWh means, how to calculate it, and what 1 kWh costs in 2026 — with real kettle & heater examples.
What is a kWh?
A kWh (kilowatt hour) is how you’re billed for energy. If your rate is 26.11p per kWh and you use 10 kWh, you pay £2.61.
10 kWh x £0.2611 = £2.61
What makes up a kWh?
kWh = kilo + Watt + hour
- kilo = 1000 (like 1kg = 1000g)
- Watt = how powerful your appliance is right now (e.g. kettle = 3000W)
- hour = how long you leave it on
So 1 kWh = using a 1000W appliance for 1 hour.
The only formula you need:
kWh = (Watts ÷ 1000) × hours
Examples at 26.11p/kWh:
| Appliance | Watts | Time | kWh | Cost @ 26.11p |
|---|---|---|---|---|
| Kettle | 3000W | 10 mins | 0.5 kWh | 13p |
| 500W Heater | 500W | 1 hour | 0.5 kWh | 13p |
| LED Bulb | 10W | 5 hours | 0.05 kWh | 1p |
Once you know this, you can work out any appliance.
Coming next: Appliances often use less than their label says — I’ll show you why in Post 3.
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Want to track this? Download my free appliance tracker — enter Watts and hours, it calculates kWh and £ for you.