Christmas lights at Dunelm vs B&Q and M&S: the price per 100 bulbs, and what they cost to run

The clocks have gone back, Christmas ranges are in the shops, and lots of us are about to find out whether last year's lights still work. LED Christmas lights cost very little to run, but the sets themselves vary a lot in price, and so does what you get for your money.

We've compared Christmas string lights at Dunelm, B&Q and M&S using the prices and details on their own websites on 25 October 2026. We've worked out a price per 100 bulbs, so you can compare sets of different sizes, and the running costs using Ofgem's current unit rate. Prices were correct at the time of writing and can change.

At a glance

• Lowest price per bulb: B&Q's 1,500 white LED set with a timer, £35, which works out at about £2.33 per 100 bulbs.
• Cheapest set: B&Q's 200 multicoloured LED set with a timer, £8.
• Clearest information: Dunelm lists the wattage and an IP44 indoor and outdoor rating for each of its own-brand sets we checked.
• No socket nearby: M&S's 100 warm white battery lights are £7, with two AA batteries and a timer, but they cost the most per bulb.
• Running costs: a 3.6W Dunelm set on for six hours a day for 40 days costs about 23p at the current price cap.

Prices compared

The shops measure length differently, so compare it with care. B&Q gives the distance from the first bulb to the last: 9.95m for the 200 set, 17.45m for the 350 and 37.5m for the 1,500. Dunelm gives a total length (24.9m for the 400 set, 34.9m for the 600) and lists a 5m cable separately. M&S lists 34.94m for its 500 set and 59.95m for its 1,000 set.

Dunelm

Dunelm's own-brand sets are mains-powered and rated IP44 for indoor and outdoor use, and each product page gives the wattage. The 400 warm white set (£15, 3.6W) has a built-in timer and a green cable that blends into a tree. The 600 set (£20, 7.2W) is on a clear cable, with different light settings and a timer. The 1,500 warm white cluster set (£45, 9W) packs its bulbs close together, which Dunelm says gives a full glow, and also has a timer. If you'd rather have colour, the 200 multicoloured incandescent-style set is £12 and uses 3.6W.

B&Q

B&Q has the cheapest sets we found: 200 multicoloured LEDs on a green cable for £8 and 350 on a clear cable for £12, both with a timer. Its 1,500 white LED set with timer, made by Premier Decorations and sold by B&Q, is £35 and has the lowest price per bulb of anything we checked. B&Q lists these sets as 31V but doesn't give a wattage, so we couldn't work out their running costs.

B&Q's website also sells lights from other companies through its marketplace. Check the "Sold & shipped by" line on the product page, because that's who you're buying from.

M&S

M&S's 100 warm white battery string lights are £7, with two AA batteries included, 9.9m of lit length and a timer that runs them for 8 hours on and 16 hours off. M&S says they're for indoor and outdoor use, so they suit a wreath or a porch with no socket nearby. Its mains sets come with a remote control: 500 warm white bulbs for £20 and 1,000 for £35, with 300-bulb sets at £14. The mains product pages we checked didn't give a wattage or say whether the sets can go outside, so check the box before you put them up outdoors.

What they cost to run

Ofgem's average electricity unit rate from 1 October to 31 December 2026 is 26.32p per kWh for Direct Debit customers. To work out a running cost, multiply the watts by the hours, divide by 1,000 and multiply by the unit rate. We've assumed six hours a day for 40 days, from late November to early January:

• Dunelm 400 warm white (3.6W): 3.6 × 6 × 40 ÷ 1,000 = 0.86kWh, about 23p for the season.
• Dunelm 600 warm white (7.2W): 1.73kWh, about 45p.
• Dunelm 1,500 cluster (9W): 2.16kWh, about 57p.

The wattage on a product page is the most a set draws, so twinkling or dimmed settings may use less. Some of those 40 days fall after 1 January, when a new price cap starts. Energy consultancy Cornwall Insight forecasts the cap will rise by 16% in January. Even if it does, that adds only pennies to these figures.

Safety: check before you plug in

Warwickshire Fire and Rescue Service warns that lights stored for a year can become unsafe. It advises checking that lights meet British Standard BS EN 60598 and looking for damaged cables or broken bulbs before you use them. It also says to switch fairy lights off before you go out or go to bed, which a built-in timer can do for you.

• Outdoors: only use lights outside if they're made for it. Dunelm's sets list an IP44 rating. If the box doesn't say a set is for outdoor use, keep it indoors.
• Your rights: under the Consumer Rights Act 2015, goods you buy from a business must be of satisfactory quality, fit for purpose and as described. On a marketplace, check who the seller is, because that's who you'd claim from.

Where each wins and falls short

• Dunelm gives the clearest information, with the wattage and an IP44 rating on every own-brand set we checked, and its 600-bulb set is good value at £3.33 per 100 bulbs. But its 200 multicoloured set costs more per bulb than B&Q's.
• B&Q has the cheapest sets and the lowest price per bulb, and the sets we checked have timers. But it doesn't list wattages, and many lights on its website are sold by other companies.
• M&S has remote-control mains sets and a battery set with a timer for places without a socket. But the battery set is the dearest per bulb, and the mains pages we checked didn't give wattages or outdoor ratings.

Your questions answered

Do battery lights cost more?

They cost more to buy per bulb. M&S's 100-bulb battery set is £7, against £3.50 per 100 bulbs for its 1,000-bulb mains set, and you'll need replacement batteries as the season goes on. They're best kept for places where you can't reach a socket.

Can I join two sets together?

Not unless the instructions say you can. The safety information for B&Q's own sets says not to connect one chain electrically to another, and not to plug a set in while it's still in its packaging.

Ways to save

Dunelm offers free same-day Click & Collect, free standard delivery on orders over £60 and 28-day change-of-mind returns. At B&Q, you can get £5 off a £30 spend when you join B&Q Club, Click + Collect is free and there's a 90-day returns policy. M&S has free Click & Collect on home orders, free standard delivery over £75 and free returns on online orders.

Sources: Dunelm: Christmas lights, Dunelm: 400 warm white LED string lights, B&Q: Christmas string lights, B&Q: 1,500 white LED string lights, M&S: Christmas lights, M&S: 100 LED warm white battery string lights, Ofgem: price cap unit rates, Cornwall Insight: 16% price cap rise forecast in January, Warwickshire County Council: festive electrical safety advice, Consumer Rights Act 2015, section 9

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