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At a glance · UK lighting, May 2026
24.67p
per kWh of electricity (Ofgem cap)
25,000h
rated LED life vs 1,000h for old incandescent
2021
UK ban on most halogens (1 September)
~80%
less power than the bulb it replaces
Unit rate: Ofgem price cap, 1 April to 30 June 2026. Halogen ban: gov.uk. A "kilowatt-hour" (kWh) is one unit of energy: the amount a 1,000W heater uses in an hour.
How much does a UK lightbulb really cost to run?
Cost to run a single bulb is a simple sum: watts, divided by 1,000, multiplied by hours on per year, multiplied by 24.67p. That gives you the annual electricity cost in pence.
A 60W incandescent on for 5 hours a day burns 109.5 kWh a year, which is £27 a year at 2026 rates. A 5W LED giving the same brightness burns 9.1 kWh, which is £2.25 a year. The bulb itself costs roughly £2 to £5 at any UK supermarket. The maths is brutal: an old bulb pays for a new LED in a matter of weeks.
The bigger number is the lifetime. Energy Saving Trust and most manufacturers rate quality LEDs at 25,000 hours. At 5 hours a day, that is roughly 13 years. The bulb you put in tonight may still be working in 2039.
Why most "save with LED" articles are misleading
Open any guide written before 2020 and the savings example compares LED to a 60W incandescent. That comparison was honest in 2010. In 2026 it is fiction. Most UK homes scrapped their incandescents years ago, and the EU phased them out for general use back in 2012. The bulb in your hallway today is much more likely to be a halogen, a CFL or an early LED, not a glowing tungsten filament.
That matters because the savings shrink as the starting point gets more efficient. The honest comparison for a 2026 UK reader is usually one of these:
- ✓Halogen to LED: a 42W halogen replaced by a 5W LED saves about 37W. Real and worth doing;
- ✓CFL to LED: a 14W CFL replaced by a 9W LED saves only 5W. Real but small. Wait for the CFL to fail;
- ✓Old LED to new LED: almost no power saving. The only reason to swap is brightness, colour or smart features.
If a guide quotes savings against incandescent and your home does not have any, the saving you read is the saving you will not see.
The lumens-vs-watts trap
Wattage measures how much electricity a bulb pulls in. Lumens measure how much light it gives out. For LEDs you want to shop on lumens. Watts on the box tell you the bill, not the brightness.
| Brightness | Incandescent | Halogen | CFL | LED |
|---|---|---|---|---|
| ~450 lm (bedside) | 40W | 28W | 9W | 5W |
| ~800 lm (ceiling) | 60W | 42W | 14W | 9W |
| ~1,100 lm (living room) | 75W | 53W | 18W | 11W |
| ~1,600 lm (kitchen) | 100W | 70W | 23W | 14W |
Equivalences are typical UK retail values; individual bulbs vary. Always read the lumen figure on the packaging, not the "60W equivalent" sticker.
Your LED switchover saving
At 24.67p per kWh — the verified Ofgem cap for 1 April – 30 June 2026.
Halogen GU10 spots (42W) are the most common UK target in 2026.
Count fittings, not rooms.
Average across the bulbs you swap.
Typical: 4W dim, 8W kitchen, 12W bright.
Current bulbs
LED replacements
Annual saving
Rates verified May 2026. Source: Ofgem energy price cap, 1 April to 30 June 2026. Bulb cost assumed £3 each.
Three hidden costs of holding onto old bulbs
1. The running cost dwarfs the bulb price
A 42W halogen GU10 on for 5 hours a day costs about £18.90 a year in electricity. The bulb itself cost £2 when you bought it. People hesitate on the £3 cost of a new LED while the bulb beside them quietly burns nine times that figure every year. The bulb price is a rounding error against the running cost.
2. You buy the old bulb 25 times
A traditional incandescent is rated for 1,000 hours. An LED is rated for 25,000. Over the LED's life you will buy and bin twenty-five incandescents, climb a ladder twenty-five times, and pay for twenty-five bulbs. Even at £1 each that is £25 of bulbs, plus the running cost gap. The "cheap" bulb is only cheap on the day you buy it.
3. Old bulbs heat the room you do not want heated
Roughly 90% of the energy a halogen or incandescent bulb uses comes out as heat, not light. That is fine in December. It is awful in July, when an air conditioner or a fan then works harder to remove the heat your light just added. LEDs run cool, which means less wasted electricity and a more comfortable room in summer.
The non-obvious insight: dimmers, spots and smart bulbs
Three traps catch UK households the first time they try a full LED switch:
1. Old dimmer switches and LEDs do not get on. A dimmer designed for incandescent or halogen loads expects a minimum wattage that LEDs do not pull. The symptoms are flickering, buzzing, or the bulb refusing to dim below half. Two fixes: buy LEDs explicitly labelled "dimmable" and, in many cases, replace the dimmer itself with a trailing-edge LED-compatible model. Plan for both before stripping a room.
2. GU10 halogen spots are still in millions of UK kitchens. When people say "all my bulbs are LED already" they usually mean the bayonet and screw fittings in their lamps. The recessed downlights in the kitchen ceiling, the spots above the bathroom mirror, the track lights in the lounge: those are very often still 35W or 50W halogens, switched on for hours every evening. Check before you assume.
3. Smart bulbs cost more than they save. A £15 smart bulb instead of a £3 dumb LED makes sense for lighting you actually control, scenes you actually use, and rooms where remote scheduling matters. For the spare bedroom you walk into twice a month, you are paying £12 for a feature you will never touch. Smart home energy kit earns its keep where you genuinely use it, and only there.
What to actually do
A practical order of operations for a UK home in 2026:
- ✓Walk the house tonight. Pull a bulb from every fitting and read what is on it. Anything marked 40W, 60W, 100W on a glass envelope is incandescent. Anything labelled "halogen" or running hot to the touch is halogen. The rest is already LED or CFL;
- ✓Replace halogens and incandescents first. Highest power saving per bulb, fastest payback. Start with the rooms you light for the longest each day: kitchen, living room, bathroom mirror;
- ✓Wait on the CFLs. Their power draw is only 50% higher than an LED. Run them until they die, then swap;
- ✓Buy on lumens, not watts. Aim for 450 lm in a bedside lamp, 800 lm for a ceiling pendant, 1,100 lm or more for a kitchen or living room;
- ✓Pick the colour temperature deliberately. 2,700K for warm and cosy living rooms and bedrooms. 3,000K to 4,000K for kitchens and bathrooms where you want clarity. Higher than that feels clinical at home;
- ✓Check dimmer compatibility before you buy 12 bulbs. If a room has a dimmer, test one LED first.
The bottom line
LED bulbs are no longer a luxury upgrade. In 2026 they are the default and they pay for themselves so quickly that the only reason not to switch a halogen is forgetting to. The savings are not magical, but they are real, and they stack: ten halogen spots replaced with LEDs save a typical UK household roughly £150 a year, and slot neatly into a broader home energy efficiency plan.
The article you read in 2015 was right about the principle and wrong about the numbers. The principle still holds. The numbers, run on the 2026 Ofgem cap, are even harder to argue with than they were back then.
Quick answers
Versus a 42W halogen on for 5 hours a day, a 5W LED saves about £16.65 a year per bulb at the Ofgem cap rate of 24.67p per kWh. Across ten halogen spots, that is roughly £150 a year. Versus a modern CFL, the saving per bulb is much smaller: usually £2 to £5 a year.
Sales of most halogen bulbs were banned in the UK from 1 September 2021. You can still use the ones you already own until they fail; you just cannot buy new general-purpose halogens. A handful of specialist types (oven lamps, some stage lighting) are exempt.
Quality LEDs are rated at 25,000 hours, measured to "L70": the point at which output drops to 70% of original brightness. At 5 hours a day that works out to roughly 13 years. Cheap bulbs and bulbs run in hot enclosed fittings often fall short of that figure, sometimes by half.
Not always. Older dimmers were built for halogen and incandescent loads and often flicker or buzz with LEDs. Buy bulbs labelled "dimmable" and, if the symptoms persist, replace the dimmer with a trailing-edge LED-compatible model. Test one bulb first before swapping a whole room.
Usually not. A 14W CFL replaced by a 9W LED saves only about £2 a year at 5 hours a day. The bulb costs £3 and you bin a working bulb. The honest answer: leave it in until it fails, then put an LED in its place.