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Is It Worth Replacing Halogen Spotlights with LED?

Swapping eight 35 W halogen spotlights for 5 W LEDs, used 3 hours a day, saves about £69.17 a year at the 26.32p per kWh price cap. At £4 a bulb (£32 in all) that pays back in about 5.6 months.

Try your own numbers

W

On the label or the bulb. Example values: a 50 W halogen and a 7 W LED.

W
h
£

Your own price. The starting figure is only a placeholder.

p/kWh

Change the area above or type your own rate from your bill.

Saving per year£69.17
Payback5.6 months
Energy saved per year263 kWh
Net after 10 years£659.69

8 × (35 W − 5 W) × 3 h × 365 days ÷ 1,000 = 262.8 kWh a year. × 26.32p/kWh = £69.17 a year. £32.00 ÷ £69.17 = 5.6 months.

Ignores price changes, bulb or appliance life and the time value of money. Heat from the old item may have been useful in winter.

Fig. 1 Eight spotlights, 35 W to 5 W, 3 hours a day.

Every formula is tested against worked examples. How we check

Hours a daySaving per yearPayback
1 h£23.061.4 years
2 h£46.118.3 months
3 h£69.175.6 months
4 h£92.234.2 months
8 h£184.452.1 months

Fig. 2 The same upgrade used for more or fewer hours.

Last checked 10/11/2026. Sources: Ofgem: Energy price cap unit rates and standing charges.

How the saving is worked out

Each spotlight saves 35 − 5 = 30 W. Eight of them for 3 hours on 365 days is 8 × 30 × 3 × 365 ÷ 1,000 = 263 kWh a year. At 26.32p per kWh that is £69.17 a year. The bulbs cost £32, so £32 ÷ £69.17 is 5.6 months. The net gain over ten years is £659.69.

What is assumed. The rate is the Ofgem price cap unit rate used on the electricity rates page, not your own tariff. Halogen spotlights are assumed to be 35 W and LEDs 5 W. The wattages and the price of the new item are examples. Use the figures on your own bulbs, appliance label and receipt.

When the answer changes

If you are on a cheaper fixed tariff the saving is smaller. At 1 hour a day the same swap takes about 17 months. Check your own unit rate on your bill and enter it in the rate box.

Common questions

Do I need a new transformer?

Mains GU10 spotlights do not. Low-voltage 12 V halogens may need a compatible driver, which adds to the cost you enter.

Is the price cap my rate?

Only if you are on a standard variable tariff. Enter the unit rate from your own bill for a better answer.

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