3 kW Convector Heater running cost — 4 h evening warm-up
A 3 kW Convector Heater (3,000 W) running 4 hours/day uses 12.00 kWh and costs £3.13/day at the Ofgem cap of 26.11p/kWh (1 July to 30 September 2026).
3 kW Convector Heater — 4 h evening warm-up: 3,000 W ÷ 1000 × 4 h × 26.11p/kWh = £3.13/day. Weekly (7 days): £21.93. Annual: £1140.48. Coverage: Large living room or open-plan space (~30 m²). Source: Energy Saving Trust (wattage, typical/indicative); Ofgem (OGL v3.0).
- Per hour
- 78.3p
- Per day (4 h)
- £3.13
- Per week (7 days)
- £21.93
- Per year
- £1140.48
Heater specification
- Rated power
- 3,000 W (3.0 kWh/h)
- Coverage
- Large living room or open-plan space (~30 m²)
- Cost per kWh (Ofgem cap)
- 26.11p
- Cost per hour
- 78.3p
Energy Saving Trust — typical 3 kW convector heater rating
How the cost is worked out
- Wattage: 3 kW Convector Heater draws 3,000 W = 3.0 kWh per hour.
- Daily use: 3.0 kWh × 4 h = 12.00 kWh/day.
- Daily cost: 12.00 kWh × 26.11p = £3.13.
- Weekly (7 days): £3.13 × 7 = £21.93.
- Annual: £21.93 × 52 = £1140.48.
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3,000 W wattage from Energy Saving Trust — Heating your home guide (typical appliance ratings) (typical/indicative). Unit rate 26.11p/kWh from Ofgem — Energy price cap unit rates and standing charges (1 July to 30 September 2026), OGL v3.0.