Oil-filled radiators are still direct electric heaters, but their slower, steadier feel can change how people use them.
A 1.5kW oil-filled radiator costs about 37p per hour at full power using 24.67p/kWh electricity.
The cost advantage usually comes from thermostat cycling and comfort pattern, not from a different price per kWh.
Current rate used: 24.67p/kWh electricity, 5.74p/kWh gas, based on Ofgem price cap, 1 April to 30 June 2026 for Direct Debit customers. Your actual tariff can differ by supplier, region, payment method and meter type.
The full-power column is the clean benchmark. The 65% column is a more realistic starting point for a thermostat-controlled heater in a warmed-up room.
| Heater size | Cost per hour | 5 hours | 7 days at 5h/day | 30 days at 5h/day | 30 days at 65% average output |
|---|---|---|---|---|---|
| 500W | £0.12 | £0.62 | £4.32 | £18.50 | £12.03 |
| 1kW | £0.25 | £1.23 | £8.63 | £37.01 | £24.05 |
| 1.5kW | £0.37 | £1.85 | £12.95 | £55.51 | £36.08 |
| 2kW | £0.49 | £2.47 | £17.27 | £74.01 | £48.11 |
| 2.5kW | £0.62 | £3.08 | £21.59 | £92.51 | £60.13 |
(watts / 1000) x hours x electricity price per kWh
For this page's 1.5kW example, 5 hours at full output costs £1.85. Used the same way for 30 days, it costs £55.51; at 65% average output it is closer to £36.08.
Short answers to the questions this page is built to solve.
At the same wattage and runtime, no. It may feel more economical if the thermostat cycles down and the room holds heat well.
The oil stores and releases heat, but the electricity used still depends on wattage, runtime and thermostat behaviour.