3 kW Convector Heater running cost — 12 h cold snap
A 3 kW Convector Heater (3,000 W) running 12 hours/day uses 36.00 kWh and costs £9.40/day at the Ofgem cap of 26.11p/kWh (1 July to 30 September 2026).
3 kW Convector Heater — 12 h cold snap: 3,000 W ÷ 1000 × 12 h × 26.11p/kWh = £9.40/day. Weekly (7 days): £65.80. Annual: £3421.45. 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 (12 h)
- £9.40
- Per week (7 days)
- £65.80
- Per year
- £3421.45
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 × 12 h = 36.00 kWh/day.
- Daily cost: 36.00 kWh × 26.11p = £9.40.
- Weekly (7 days): £9.40 × 7 = £65.80.
- Annual: £65.80 × 52 = £3421.45.
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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.