LED Bulb Savings Calculator

LED bulbs use 75 to 85% less electricity than traditional incandescent bulbs and 50 to 60% less than halogen bulbs for the same brightness. A 10W LED produces the same light, 800 lumens, as a 60W incandescent or a 42W halogen. The difference in working life is wider still, since an LED runs for 15,000 to 25,000 hours where an incandescent gives up after roughly 1,000. That single gap is what makes the swap pay, even though the LED costs more on the shelf.

At an electricity rate of 26.32p per kWh, replacing one 60W incandescent used four hours a day with a 10W LED saves £19.21 a year. Do that across 20 bulbs and the household saving passes £350, against an upfront cost of £2 to £8 a bulb that is recouped within a few months. Over a full 25,000 hours the arithmetic is starker. The LED burns £65.80 of electricity against £394.80 for the incandescent, a saving of £329 a bulb, and you avoid buying the five replacement incandescents (£5 to £10) needed to cover the same hours. Spread across the 30 or more fittings in an average home, that is close to £10,000 of lifetime savings.

This calculator asks for the number and type of bulbs you have now, incandescent, halogen or CFL, along with their wattage and average daily use. It returns the annual saving, the payback period and the total saved across the lifespan of the LED replacements. Household lighting follows the same pattern at scale. A home on old bulbs burns 800 to 1,200 kWh a year on lighting alone, falling to 80 to 150 kWh once every fitting is LED. That is worth about £190 a year, or £250 to £400 where the lights are on for long stretches, with the bulb cost usually repaid in 12 to 24 months and a return of 100 to 200% over five years.

Lifespan claims on the box deserve a close look. Quality bulbs are rated for 25,000 to 50,000 hours, which in a UK home works out at 20 to 40 years of use, while cheap ones manage 5,000 to 15,000 hours, or four to eight years. Unbranded eBay and AliExpress bulbs often fail after 1,000 to 3,000 hours, which wipes out the payback the calculator shows. Look for an L80 rating, meaning the bulb still gives 80% of its original brightness after 25,000 hours, a five-year manufacturer warranty from the likes of Philips, Osram or Crompton, and a colour rendering index of 80 or above for natural-looking light.

Colour temperature changes how a room feels rather than what it costs to run. 2700K reads as warm and suits living rooms, 4000K is neutral and works well in kitchens and bathrooms, and 6500K daylight belongs in workshops and retail spaces. Downlights are where the savings concentrate, because a GU10 spotlight swaps a 50W halogen for a 5W LED at roughly ten times the efficiency, for £4 to £10 a bulb. Bathroom fittings need an IP65 rating for water resistance, and on a dimmed circuit the bulb has to match the switch, since most modern LED dimmers are leading-edge. Older fittings take bayonet or screw caps, B22 and E27, and both are easy to find. Building Regulations Part L has required LED lighting in new builds and major refurbishments since 2022.

Smart bulbs sit on top of all this rather than replacing it. Philips Hue is the premium option at £15 to £35 a bulb plus a hub costing £40 to £60, controlled by app and voice assistant. IKEA Tradfri undercuts it at £8 to £15, LIFX and Govee connect straight to WiFi with no hub for £12 to £25, and Sengled and Yeelight sit lower again. What you buy is scheduling, dimming, colour change and away-mode, which matter most for security and accessibility. The catch is that a connected bulb draws 0.3 to 0.5W even when it is off, so 20 or more of them add £8 to £15 a year. Smart switches at £15 to £40 give similar control over ordinary bulbs.