The formula
Cost per hour = power in kW × price per kWh × share of time at full power
- Power: the K1 is rated at 1200W, which is 1.2 kW.
- Price: 26.32p per kWh, the Ofgem price cap average for electricity paid by Direct Debit, 1 October to 31 December 2026. Source: Ofgem: energy price cap unit rates and standing charges, checked 25 October 2026.
- Share of time at full power: once the room reaches the set temperature, the thermostat switches the heater on and off. We assume it runs at full power 50% of the time in typical use. In a cold or draughty room it will be higher.
Worked example
At full power: 1.2 kW × 26.32p = about 32p an hour. In typical use: 32p × 50% = about 16p an hour.
What it costs to run (current UK prices)
At the Ofgem price cap of 26.32p per kWh (1 October to 31 December 2026), a 1200W heater like the K1 costs about 32p an hour at full power. Once the room is warm the thermostat switches the heater on and off, so in normal use it averages about 16p an hour.
| How long | Typical cost per day | Over 30 days |
|---|---|---|
| 1 hour | 16p | £4.74 |
| An evening (4 hours) | 63p | £18.95 |
| A working day (8 hours) | £1.26 | £37.90 |
Your own price may be a little higher or lower depending on your region and tariff. See how we calculate running costs or try the running cost calculator with your own unit rate.
What can change your cost
- Your region and tariff. Unit rates vary across the UK, and fixed tariffs differ from the price cap.
- How cold, big and well insulated the room is.
- The thermostat setting you choose.
- Economy 7 and other time-of-use tariffs charge different rates at different times.
We update these figures when Ofgem changes the price cap, usually every three months. Use the running cost calculator with your own unit rate from your bill.
What we don't claim
No electric heater turns more than about 100% of its electricity into heat. Any saving comes from heating only the room you're in, not from special technology. We don't promise a fixed reduction in your bills.