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How to buy the best light bulb

Everything you need to know about CFLs, LEDs, halogens and smart light bulbs, including energy efficiency, annual costs and how to get rid of your old bulbs
Which? Team
Lightbulbs 1

There are three types of energy-saving light bulb: compact fluorescent lamps, known as CFLs (the most common type of light bulb); halogens (which are now banned from sale); and LEDs.

In this expert guide, we'll help you to choose the right light bulbs for your home, whether you're shopping for standard bulbs or a multipack of internet-enabled smart bulbs. Opt for smart bulbs and you'll be able to control your lights using your voice or from your mobile phone.

Below, we explain the key differences between types of light bulb. Plus, we have information on choosing the correct bulb brightness and colour, along with instructions on what to do with your old, retired bulbs.

Aside from swapping out your old light bulbs, there are plenty of other ways to lower your energy bill. Read our advice on how to make your home more energy efficient.

Halogen vs CFL vs LED vs light bulbs: what's the difference? 

Our table shows at a glance how these light bulb types compare for lifespan, typical cost and energy use – we delve into more detail on the pros and cons of each type later in this article.

Halogen light bulbs
CFL light bulbs

LED light bulbs
Estimated lifespan2,000 hours
10,000 hours25,000 hours
Typical cost£2-7*
Energy use
(compared with incandescent bulbs)
20-30% less
60-80% less90% less
Suitable for low temperaturesNo
* Halogen light bulbs are now banned from sale in the UK

As you can see from our table, LEDs are miles ahead of CFLs and halogens in terms of estimated lifespan, although they're usually the most expensive to buy.

LEDs are also the most energy-efficient option, using 90% less energy than traditional incandescent bulbs, which were phased out in the UK in 2009. Although the upfront cost might be high, you'll notice the difference in your annual energy bills. By contrast, CFLs use 60%-80% less energy than incandescents, while halogens use 20-30% less.

When thinking about where to position your bulbs, note that LEDs work fine in low temperatures, whereas CFLs don't. Halogen bulbs will also struggle in cold temperatures.

Lightbulbs 5

The phase-out of halogen and fluorescent light bulbs

Old-style 'high-energy' incandescent bulbs stopped being sold in the UK from 2009, but they're not the last light bulb to face the chop because of their relatively poor energy efficiency. In October 2021, the UK government banned the sale of halogen light bulbs in an effort to 'cut emissions and save consumers on their energy bills'.

The government says 'high-energy' fluorescent lights (including traditional, tube-style fluorescent lights commonly found in offices) will follow suit. The plan is to start removing these lights from retailer shelves from September 2023, and there's now a good range of LED strip-light alternatives. 

Compact fluorescent lamps (CFLs) are low-energy bulbs (although not as low as LEDs), so don't appear to be part of the planned ban. However, we expect that manufacturers will stop producing them over the coming years, regardless of any ban, as their focus shifts to LEDs. We recommend opting for LEDs where possible, as they'll be sticking around for years to come.

A post on Gov.uk notes that a shift to LED bulbs 'will cut 1.26 million tonnes of CO2' – the equivalent of removing more than half a million cars from UK roads. Additional figures claim that around two thirds of bulbs sold in Britain are LED lights and that, while they produce the same amount of light, these last 'five times longer' than traditional halogen light bulbs.

There's a chance you'll find a couple of dusty halogen light bulbs still on sale at your local DIY store, but retailers will no longer be able to buy new stock once shelves are empty.

To help consumers understand the benefit of replacing halogens and fluorescent light bulbs with the most energy-efficient alternatives, all new light bulbs will be sold with updated energy labels on their boxes.

A new, simpler scale, running from A-G, will replace the old (and slightly bewildering) A+, A++ and A+++ ratings. The Gov.uk website says these labels will 'raise the bar for each class, meaning very few bulbs will now be classified as A, helping consumers choose the most environmentally friendly bulbs.'

CFL light bulbs explained

What are CFL light bulbs?

Compact fluorescent lamp (CFL) light bulbs are the original energy-efficient alternative to now-defunct traditional incandescent bulbs. CFLs typically use 60-80% less energy than an incandescent, while halogens use 20-30% less and LEDs use an astonishing 90% less.

With the government looking to remove 'high-energy' fluorescent lights from shelves from 2023, and an increasing industry focus on the move to LEDs, we anticipate that CFLs will gradually become harder to find. Manufacturers will gradually stop producing CFLs as more buyers transition to LEDs.

Old-style incandescent bulbs had a filament inside that was heated until it glowed, which meant they used up energy to generate heat. CFL bulbs don't have a filament. Instead they use an electric current to excite gases within the bulb that then cause a phosphorous coating on the inside to glow, producing light. This method means less energy is lost to heat and the bulb uses less energy overall. Some CFLs take a few minutes to reach full brightness.

CFL bulbs come in stick and spiral shapes, although some are now disguised as traditionally shaped bulbs. They typically cost between £3 and £15.

Most modern dimmer switches should work with CFL bulbs, although some older ones might not be compatible.

Pros of CFLs:

  • CFLs are reasonably cheap to buy, with prices starting as low as £3.
  • They pay for themselves with energy savings fairly quickly. Replacing just one 60W incandescent with a CFL bulb can reduce your electricity bill by around £7 a year.
  • CFL light bulbs have a long lifespan of around 10,000 hours (or roughly about 10 years of use).

Cons of CFLs:

  • They take a bit of time to warm up and get bright when they're first switched on. This means CFLs aren't always the best choice for stairs or bathrooms.
  • Some CFLs aren't suitable to use with dimmer switches.
  • These bulbs tend to work poorly in cold temperatures, making them less suitable for unheated rooms or outdoor spaces, such as a garage.
  • Some CFLs look significantly different compared with old-style bulbs and it can be tricky to get them in certain shapes and sizes, such as small candle bulbs.
  • We expect that CFLs will become harder to obtain over coming years as the industry shifts its focus more fully on to LEDs.

LED light bulbs explained

What are LED light bulbs?

LED lights have been hailed as the future of home lighting, as they use very little energy, are claimed to last a very long time and, unlike regular energy-saving bulbs, are instantly bright when switched onMost smart light bulbs (see below) are LEDs.

While old-fashioned incandescent light bulbs passed electricity through a thin wire filament, LEDs produce light through the use of a semi-conductor that emits light energy when an electrical current is passed through it.

Early LEDs were limited by high prices and relatively low light output, but the technology has developed rapidly in recent years. You can now get bright, efficient LED bulbs that give out as much light as 100W old-style bulbs and look just like a traditional bulb.

Plus, prices are getting lower all the time. While the brightest bulbs can still set you back around £20, most cost less than £10, and the energy savings they will provide in your home make them well worth considering.

Pros of LED bulbs:

  • LEDs use 90% less energy than traditional incandescents, and can sometimes pay for themselves through energy savings in just a couple of months.
  • These light bulbs can last for 25-30 years, depending on which ones you buy and how you use them.
  • They give out light almost instantly when you flick the light switch, so you don't have to put up with dim light while your LEDs get going.
  • They work fine in low temperatures.

Cons of LED bulbs:

  • Some people don't like the quality of light given out by LED light bulbs, as they can produce a cooler, bluish light.
  • To dim LED lights, you might need to upgrade to a dimmer that recognises low electrical loads. The packaging should say whether LEDs are dimmable.
  • It's tricky to get a consistent look in your home if you mix different LED brands and types. The colour temperature and colour rendering index (CRI) can vary more than with traditional light bulbs.

Can LED light bulbs affect digital radios?

All electrical appliances, including light bulbs, emit electromagnetic interference (EMI), although this is tightly controlled within the EU. In some rare cases, EMI can impact the DAB radio signal.

We've previously tested lower-priced LED bulbs for radio interference, but haven't found any bulbs that caused a problem. Despite this, we do know that 1-2% of Which? members have experienced this issue.

If you're having trouble with radio interference, check that your bulbs have a CE mark and replace them if they don't. If this doesn't fix the issue, it could be a problem with your setup, so consult an electrician.

Smart light bulbs explained

What are smart light bulbs?

Smart light bulbs are internet-connected and controllable from anywhere in the world, as long as you have a data or wi-fi connection. Although you'll find some incandescent smart lights if you shop online, most are powered by LEDs.

When setting up a smart lighting system, you'll usually need to buy a smart hub – this allows your bulbs to communicate with your router, which makes them internet-enabled. The smart hub connects to your router via an ethernet cable. Once it's set up, you can start adding bulbs to your smart lighting system. But you'll need to make sure these two components are compatible – for example, Philips smart bulbs will only work with a Philips Hue Bridge.

Some smart bulbs will still function without a smart hub. For example, certain bulbs from LIFX have built-in wi-fi, which means they work independently.

We've also seen smart lights that work over Bluetooth as well as (or instead of) wi-fi. This means that although you can control the bulbs remotely using a phone or tablet, you need to be within a specific range. For example, Philips Hue sells smart bulbs (controlled through the Philips Hue Bluetooth app) that have a Bluetooth range of 'about 30 feet.' But as Bluetooth bulbs aren't connected to the internet via a smart hub, you can't control them when you're out of the house.

When shopping for a smart light bulb, make sure you pick a bulb that matches your existing fitting. Philips, for example, sells bayonet, Edison screw and GU10 bulbs. 

If you're replacing old halogen fittings with LED smart bulbs, you'll be pleased to hear that your new lights have a much longer lifespan. The downside is that if you're replacing lots of lights in your home with smart bulbs, initial costs can be high.

Smart bulb features and costs

You can turn smart bulbs on and off at via an app, and most smart lighting systems are compatible with voice commands through Google Assistant or Amazon's Alexa. You can try saying 'OK, Google, turn the living room lights down to 20%', for example.

Many smart bulbs can change colour , so you can change the appearance of your living room depending on your mood or the time of day. You can expect to spend up to around £50 for a single, colour-shifting smart bulb. If you're shopping for a smart bulb that just switches between warmer and cooler white tones, expect to pay £10-30.

Pros of smart light bulbs

  • You can control smart light bulbs while out of the house, which is handy if you accidentally leave a light on.
  • Smart bulbs are made with existing lamps and light fixtures in mind and most come with Edison caps, bayonet caps or both.
  • As an extra layer of security, you can turn on your lights remotely to deter burglars.
  • Many smart home hubs come with motion sensors – you can set them so that your smart bulbs turn on when they detect movement.

Cons of smart light bulbs

  • If you're looking to upgrade multiple 'regular' bulbs to smart alternatives, costs can ramp up.
  • You won't be able to control your smart light bulbs remotely if you have wi-fi or mobile signal issues.
  • Bluetooth-only smart bulbs can't be controlled beyond a certain distance.
Used philips hue 468896

Halogen light bulbs explained

What are halogen light bulbs?

Halogen light bulbs comprise a filament enclosed in halogen gas, meaning they can burn hotter than an incandescent but still use less energy. While they're more energy efficient than traditional incandescent bulbs and were once a decent choice, technology has moved on and there are now much more environmentally friendly options. 

Because of this, halogen lights have now been banned from sale.

Should I replace my existing halogen light bulbs?

With halogens now banned from sale in the UK, you might be wondering whether it's time to replace your own halogen bulbs.

Halogens are more expensive to run than LEDs and they don't last nearly as long, so we suggest swapping out your halogens sooner rather than later. Don't wait for your halogen bulbs to die before making the switch to an environmentally friendly LED.

Three tips for choosing the right light bulb

1. Buy a light bulb with the correct fitting and shape

Make sure the bulb fitting and shape matches the one you're replacing by cross-checking the fitting reference number. If you're buying in store, it could help to take the old bulb with you. If not, write down the fitting reference number and match it with the packaging on the box of your new bulb.

Our graphic, below, shows some of the most common fittings.

Light bulb fittings 444377

You also need to think about which bulb shape you want – there's a bewildering variety, and different brands have a subtly different look and characteristics.

Light bulb shapes 443330

Each of the different shapes provides a slightly different spread and angle of light, from the almost 360-degree spread of a globe or golf bulb, to the narrow beam of a spotlight. The 'right' shape of the bulb and spread of the light is essentially down to your personal preference, but consider how the bulbs will look when they're switched off as well as on, and whether they will fit sensibly in their chosen location. For example, you wouldn't want a large stick shape if it will protrude from the top of your bedside lamp.

2. Don't be put off by the upfront cost of LED lights

LED light bulbs could save you hundreds of pounds in the long run.

A typical 700+ lumen LED bulb will cost you around £1.71 a year, based on three hours of use every day. For a CFL alternative that would be £2.04, or £8.42 if you use an existing halogen bulb.

3. Get the right light bulb brightness and colour

Watts and lumens (brightness)

Since the introduction of energy-saving bulbs, wattage is a less useful measure of brightness, as new bulbs use a lot less power to produce the same amount of light. So, instead, light output is measured in lumens. The higher the number of lumens, the brighter the light.

As a rough guide, around 400 lumens would typically be suitable for a bed-sized table lamp, whereas you might want between 1,500 and 3,000 lumens in total (from more than one bulb) for a good-sized living room.

Equivalent wattage 443915

Kelvin scale (colour)

The colour of light is measured on the Kelvin scale, which is actually a measure of temperature. This is why light bulb manufacturers often refer to 'colour temperature' on the packaging. The numbers you see on the side of the bulb packet denote the colour of light that the bulb will emit.

Most people have become used to the warm, yellowy light given out by the old incandescent bulbs, which is 2,700 on the Kelvin scale. Midday sunlight is about 5,500k, sunset or sunrise lighting is around 2,500k and a candle is around 1,600k.

Kelvin and atmosphere 443329

CRI (colour rendering index)

Every bulb is given a CRI score. CRI stands for colour rendering index and is a measure of the ability of a light source to accurately represent different colours. Put simply, you want to make sure you get a bulb that makes your tomatoes look red, rather than a strange orangey colour. 

Traditional incandescent and halogen bulbs have a near-perfect CRI and score in the high 90s. LEDs and CFLs are a little behind this and are more likely to have a CRI value in the mid 80s. 80 is considered an acceptable level, although like many things it comes down to personal preference.

The image below shows the impact of CRI – the left-hand image is shot under light with a CRI value of 100, while the image on the right has a CRI value of 80.

Light comparison 442929

Where to buy light bulbs

Several popular online retailers stock light bulbs.

  • Amazon has a massive selection of light bulbs, including budget-priced smart bulbs and energy-efficient LED multipacks.
  • Argos sells a selection of light bulbs split by category: Edison screw (ES), bayonet (BC), small Edison screw (SES), GU and smart bulbs.
  • B&Q has a mix of LED bulbs, decorative LEDs and smart bulbs. 
  • Ikea has hundreds of light bulbs to choose from, including £2 LEDs as well as internet-connected bulbs that live within the brand's Ikea Home Smart ecosystem.
  • Lightbulbs Direct offers a wide selection of LEDs and CFLs.
  • Screwfix sells regular LED lights alongside smart light bulbs from big-name brands including Hive, Philips Hue and TCP.

Find out which retailers are rated highly by Which? members with our expert guide on the best and worst shops.

How to dispose of your old light bulbs

  • CFL bulbs – If you want to get rid of an old CFL bulb, avoid chucking it in with your regular rubbish. CFL bulbs contain tiny amounts of mercury, which means they'll need to go to a recycling centre or one of your local recycling drop-off points.
  • LED bulbs – These last a long time, so you shouldn't need to get rid of one often. If one of yours finally conks out , you can just chuck the bulb in your normal household waste. Bear in mind that warranties on LED bulbs typically last between two and four years, so if the bulb fails within this time you should be able to get your money back. Check the box for details, and contact the retailer or the manufacturer’s customer service department.
  • Halogen bulbs – These aren't recyclable because they contain a series of fine wires which are difficult to separate out. Wrap the bulb in case it shatters, then put it with your normal household waste.

For more details on getting rid of your old electronics, see our expert guide on how to recycle electrical items.

Do CFL light bulbs pose a health risk?

CFL light bulbs have been anecdotally linked with certain health conditions – here's what we know about them.

Do energy-saving CFL light bulbs cause cancer?

The Health Protection Agency (HPA) issued a warning in October 2008 about some energy-saving light bulbs emitting higher levels of UV radiation than guidelines suggest is safe.

It suggests, as a precaution, that spiral and tube-type energy-saving CFL light bulbs shouldn’t be used for more than one hour a day if you're less than 30cm away from the bulb, such as a desk lamp. Instead, you should switch to globe-style bulbs, or move the lamp further away.

The HPA is keen to point out that CFL light bulbs won't directly cause skin cancer. But sitting very close to a light bulb that emits more than the recommended amount of UV light has similar effects to going outside on a sunny day – so some caution is recommended.

There’s no need to panic and replace all your CFL light bulbs.

Can CFL light bulbs trigger epilepsy?

The charity Epilepsy Action has some anecdotal reports from people who believe ill effects, such as headaches and dizziness, have been caused by energy-saving light bulbs.

It has said: 'Epilepsy Action isn't aware of any evidence that low-energy light bulbs can directly trigger epileptic seizures in people with photosensitive epilepsy. However, we have been contacted by a number of people with epilepsy who believe that energy-saving light bulbs have impacted on their condition.

'We aren't able to quantify how many people with epilepsy are affected by these bulbs, or say definitively how energy-saving light bulbs may affect people with epilepsy. We're asking the government to confirm that ordinary light bulbs will still be available for people with epilepsy, should they have concerns about the use of energy-efficient light bulbs and their epilepsy. We will continue to monitor the situation.'

Do CFL light bulbs cause migraines?

Some migraine support groups, such as the Migraine Action, have raised this as a concern.

The Department of Health has said in response: 'The Department is aware of concern from migraine support groups that the use of some energy-saving light bulbs could potentially affect migraine sufferers. We're continuing to work with clinicians and support groups regarding the nature and extent of any reported health effects, and bring influence to bear where appropriate.' 

Although we're yet to see concrete evidence linking CFLs with migraines, if you suffer from migraines you might wish to try a different type of bulb. Standard painkillers might barely scratch the surface of a migraine, but they can be effective with more minor aches and pains, as long as you pick the right type. 

Find out which works best for different ailments with our expert guide to the best painkillers: aspirin, ibuprofen or paracetamol?