Working out how much it costs to run LED lights takes one short sum. A 6W LED bulb costs about 0.16p an hour to run at the electricity rate used in this guide. Run it five hours a day and it costs about 23.69p over 30 days, or about £2.88 a year. The method below lets you swap in your own wattage, hours and unit rate.
Key Takeaways
- The sum is wattage divided by 1,000, multiplied by hours used, multiplied by your electricity price per kWh.
- At 26.32p per kWh, one 6W LED bulb costs about 0.16p per hour.
- Left on for a full 24 hours, that same bulb costs about 3.79p, or about £13.83 over a year.
- Ten 6W bulbs running five hours a day come to about £28.82 a year.
- Your own figure depends on wattage, hours, bulb count and your tariff.
- The daily standing charge is not part of the sum, because you pay it whether or not the light is on.
The quick answer: One 6W LED bulb costs about 0.16p per hour. Five hours a day makes that about 0.79p a day, 23.69p over 30 days and £2.88 over a year. A 50W halogen bulb in the same position and the same hours would cost about £24.02 a year. Running cost scales directly with wattage and hours, so doubling either doubles the cost.
The Electricity Rate Used in This Guide
Every figure here uses Ofgem's average electricity unit rate of 26.32 pence per kWh for 1 October to 31 December 2026. That figure is the price cap level for households on a standard variable (default) tariff paying by Direct Debit, averaged across England, Scotland and Wales.
Two things to note. Ofgem states that this electricity figure does not include VAT, because the government removed VAT from electricity bills from 1 October 2026 to 31 March 2027. Ofgem also states that the amount you actually pay depends on how much energy you use, where you live and the type of meter you have.
So treat 26.32p as a reference point, not as your rate. A fixed tariff, a prepayment meter or an Economy 7 meter will each give a different unit rate. So will simply living in a different region. Your bill or your supplier's app will show the figure to use instead.
How to Work Out What Your LED Lights Cost to Run
The formula:
Cost = wattage divided by 1,000, times hours used, times price per kWh
Dividing by 1,000 turns watts into kilowatts, which is what you are billed in.
Worked through with a 6W LED bulb used five hours a day:
- 6 divided by 1,000 = 0.006 kW
- 0.006 times 5 hours = 0.03 kWh per day
- 0.03 times 26.32p = 0.79p per day
- 0.79p times 365 = 288.2p, or £2.88 a year
Swap in your own four numbers and the answer changes accordingly. Nothing else is needed.
LED Running Costs per Hour, Day, Month and Year
These scenarios use illustrative wattages. They are not a claim about what every LED bulb draws, so check your own bulbs before using any row as your answer.
| Scenario | Per hour | Per day | Per 30 days | Per year |
|---|---|---|---|---|
| One 6W LED, 1 hour a day | 0.16p | 0.16p | 4.74p | 57.64p |
| One 6W LED, 3 hours a day | 0.16p | 0.47p | 14.21p | £1.73 |
| One 6W LED, 5 hours a day | 0.16p | 0.79p | 23.69p | £2.88 |
| One 8W LED, 5 hours a day | 0.21p | 1.05p | 31.58p | £3.84 |
| Ten 6W LEDs, 5 hours a day | 1.58p | 7.90p | £2.37 | £28.82 |
| One 6W LED, left on 24 hours | 0.16p | 3.79p | £1.14 | £13.83 |
Figures are calculated at 26.32p per kWh and rounded to two decimal places, shown in pence below £1 and in pounds above it. A 30 day month and a 365 day year are used.
What It Costs to Leave an LED Light On All Day
The 24 hour row is there as an illustration rather than a suggestion. A 6W LED left on continuously costs about 3.79p a day. Over a 30 day month that is about £1.14, and over a year about £13.83.
That is a small number for one bulb. It applies to one 6W bulb only. A room with six fittings left on all day multiplies it six times.
How the Number of Bulbs Changes the Total
Running cost scales directly with the number of bulbs, so the arithmetic stays simple. One 6W LED at five hours a day is about £2.88 a year. Ten of them in the same pattern come to about £28.82 a year.
Kitchens and open plan spaces are where this adds up, because spotlights are fitted in groups. Count the actual bulbs in the fitting rather than counting the fitting as one.
LED Versus Halogen Running Cost
If you are replacing a halogen bulb rated at 50W with an LED rated at 6W, and both are run five hours a day, the comparison at 26.32p per kWh looks like this:
- 50W halogen: about 6.58p a day, or about £24.02 a year
- 6W LED: about 0.79p a day, or about £2.88 a year
That is a difference of roughly £21.13 per bulb per year in this scenario.
Two cautions. These are illustrative wattages, not a claim about every bulb pairing. Wattage on its own also does not prove two bulbs give similar light. Check the lumen figure on the packaging before treating one as a replacement for the other. Our guide to how many lumens you need covers brightness, and the LED bulb replacement guide covers which LED suits which old bulb.
Why Your Bill May Not Match These Figures
Four inputs change the answer: the wattage of your bulbs, how many you run, how long you run them, and your unit rate. Change any one and every figure above moves.
The standing charge is deliberately left out. It is a fixed daily amount for being connected to the network, and you pay it whether or not any particular light is switched on. Adding it to a single bulb's running cost would overstate what that bulb costs you.
Does Switching LED Lights Off Still Matter?
Yes, though the saving per bulb is small. Switching off a 6W LED that would otherwise run an extra three hours a day saves about £1.73 over a year.
The saving grows with wattage and with the number of bulbs involved. Where it matters most is the lights that get left on by default: hallways, outbuildings and spotlight groups in rooms nobody is using.
How to Check the Wattage of Your Bulbs
- Look at the printing on the bulb itself, usually near the cap or on the glass.
- Check the packaging, which gives wattage and lumen output.
- Check the product page where you bought it.
- Note the figure for the bulb, then multiply by how many sit in the fitting.
If a bulb lists both an actual wattage and an equivalent wattage, use the actual figure in the sum. The equivalent is a brightness comparison, not the power the bulb draws.
Frequently Asked Questions About LED Running Costs
How much does it cost to run an LED light per hour?
At Ofgem's average electricity rate of 26.32p per kWh for 1 October to 31 December 2026, a 6W LED bulb costs about 0.16p per hour and an 8W bulb about 0.21p. Work out your own figure with wattage divided by 1,000, multiplied by hours, multiplied by your unit rate. Your tariff and region will change the result.
How much does it cost to leave an LED light on all day?
A 6W LED left on for a full 24 hours costs about 3.79p at 26.32p per kWh. Over 30 days that is about £1.14, and over a year about £13.83. Those figures are for one bulb, so multiply by the number of bulbs in the fitting or the room before deciding whether it matters to you.
Do LED lights use a lot of electricity?
Not in the sense the question usually means. A 6W LED bulb run five hours a day uses about 11 kWh of electricity over a year, which costs about £2.88 at 26.32p per kWh. The more useful question is how many bulbs you run and for how long, because a group of ten spotlights costs ten times as much to run as one bulb in the same pattern.
Does switching LED lights off still save money?
Yes, though the amount per bulb is small. Cutting three hours a day from one 6W LED saves about £1.73 over a year at 26.32p per kWh. The saving is larger with higher wattage bulbs and with the spotlight groups found in kitchens, so the lights worth switching off are the ones left on in empty rooms.
Is an LED cheaper to run than a halogen bulb?
For the same hours, running cost follows wattage, so a lower wattage bulb costs less to run. A 50W halogen run five hours a day costs about £24.02 a year at 26.32p per kWh, against about £2.88 for a 6W LED. Check the lumen figures before assuming two bulbs give similar light, as wattage alone does not show brightness.
Why is my electricity bill different from these figures?
These calculations use one reference rate, Ofgem's average for default tariffs paid by Direct Debit across England, Scotland and Wales. Your unit rate depends on your supplier, tariff, region, meter type and payment method. Your bill also includes a daily standing charge, which is not part of any individual bulb's running cost.
Choosing LED Bulbs for Your Fittings
Running cost follows wattage and hours, so the practical decision is matching the right bulb to each fitting and then not leaving it on out of habit. Check the cap type first, then the brightness in lumens, then the wattage you will be paying for.
Lumination stocks GU10 LED bulbs for spotlights and downlights, and B22 bayonet LED bulbs for pendants and lamps. If you are not sure which cap you have, the team in our Taunton (145 East Reach) and Wellington showrooms can identify it from the old bulb. Delivery is free on UK orders over £75, and returns are accepted within 14 days.
