Light bulb types and fittings

Find the light bulb you need with our guide to the different types, sizes and fittings.

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Light bulb types and fittings.

Light bulb types and fittings

All light bulbs have a code to identify their type and fitting. The letters usually stand for name of the fitting and the numbers are the diameter of the fitting in millimetres. There are usually LED and halogen options for both.


ES stands for Edison Screw and is one of the most common types of fitting. These light bulbs use a screw motion to slot into the fitting. The two types of ES are the E27 and the thinner E14 (sometimes called an SES).

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BC stands for bayonet cap. These bulbs use a twist and lock action to secure into the fitting, and the most common type is a B22.

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G4 and G9s, or capsule bulbs, are similar to bayonet caps, in that they need to be pushed in, twisted and locked. Most commonly used in cooker hoods.

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Also known as spotlight bulbs, they have two pins that connect into the spotlight socket.

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This type of halogen bulb is commonly used in security lighting and floodlights.

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Standard bulbs

The most commonly found shape of bulb, used across the home in lamps and ceiling lights.

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Capsule bulb

Capsule bulbs are most likely to be required for kitchen and appliance lighting.

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Candle bulb

Candle bulbs offer decorative style, as they are intended to look like the flame from a candle.

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Spotlights are fitted in the ceiling and are popular in both kitchens and bathrooms.

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Linear lighting

Frequently used in floodlighting and security lighting due to their increased brightness.

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LED vs Halogen

Benefits of LED light bulbs

LED light bulbs will soon be the only type of bulb that you can buy in the UK. LED bulbs can last up to 25 years, far longer than halogen bulbs, which may need replacing after 1 year of use. LEDs are far more cost effective, saving you up to £240 a year, while halogens produce more heat and use 85% more power.

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Wattage and lumens

Together, wattage and lumens define the brightness and energy efficiency of a light bulb. LED lights tend to give you more lumens, for far less wattage than halogen.

Light bulb wattage

Wattage tells you how much power a bulb uses. More watts equal more power, but it doesn’t mean more brightness – for that you need to look at the lumens.


More lumens mean a brighter light. And for the greatest energy efficiency, you want to choose a bulb with the most lumens and least wattage.

Warm or cold lighting?

Some light bulbs have warm and cold tones, which is rated in kelvins. Candlelight is around 1,500 kelvins and 10,000 kelvins is equal to a blue sky. Standard bulbs have around 2,700 kelvins, but there are a range of options, letting you set the mood you want in your home.

Light bulb top picks

More help and inspiration

Lighting buying guide

Your in-depth guide to lighting up your home.

Read our lighting buying guide

Kitchen lighting ideas

Bright ideas for choosing lights in your kitchen.

View kitchen lighting ideas

Bathroom lighting ideas

Let the light into your bathroom with inspirational ideas.

View bathroom lighting ideas

Smart lighting

Home lighting that you can control from your phone.

Shop smart lighting

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