Which bulb fitting do I need?

Written by: Jon Duffy



Time to read 3 min

Blown a bulb? Thinking of switching to LED lighting? Want to add smart control to your lights? Whatever your reason for searching for a new bulb, explore our range of lightbulbs here at Maplin to find exactly what you’re looking for. It’s important to know what size fitting you need for the bulbs you’re replacing. So which bulb fitting do you need? If you’re not sure, check out our handy guide to buying the best bulb for you.

Which bulb fitting do I need?

E14 light bulb fittings at Maplin
E27 light bulb fittings at Maplin

E14 / E27

Also known as Edison caps, E14 and E27 bulb fittings resemble a screw shape with the number referring to the diameter of the fitting. This means E14 fittings are thinner than E27, but still have the distinctive screw shape.

E14 and E27 bulbs are two common types of light bulbs widely used in households and commercial spaces. The "E" in their names refers to the Edison screw base, a standardized screw base design developed by Thomas Edison for light bulbs. Both E14 and E27 bulbs are available in various shapes, sizes, and wattages, making them versatile options for lighting fixtures such as table lamps, ceiling lights, and pendant lights. While E14 bulbs are commonly used in smaller fixtures and decorative lighting, E27 bulbs are favoured for larger fixtures and general lighting applications. 

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Shop E27 bulbs

B22 light bulb fittings at Maplin


Bayonet bulbs use a twist and lock motion to install. Unlike the Edison caps, they instead feature two prongs on either side. Widely used in most UK homes, you simply need to push and twist the bulb to connect it.

B22 bulbs are characterized by their distinctive bayonet fitting. The "B" in their name refers to the bayonet cap base, which features two pins on the bulb's base that slot into corresponding spring-loaded slots in the light fixture. This design ensures a secure and reliable connection between the bulb and the fixture, preventing the bulb from coming loose or falling out. B22 bulbs are commonly used in households and commercial spaces. Like E14 and E27 bulbs, B22 bulbs are available in various shapes, sizes, and wattages, catering to a wide range of lighting needs. They are compatible with a variety of light bulb technologies, including incandescent, halogen, CFL (compact fluorescent), and LED (light-emitting diode), offering users flexibility and choice when it comes to selecting the right bulb for their lighting fixtures.

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GU10 light bulb fittings at Maplin


GU10 bulbs are commonly used for spotlights or downlights in kitchens or bathrooms. They connect via two pins on the base of the bulb. Suitable for both domestic and commercial use, they feature tiny glass surfaces on the inside that help to bounce light around the room.

They are commonly used in track lighting, recessed ceiling fixtures, and spotlighting applications. The "GU" in their name stands for "G" meaning "glass" and "U" meaning "twist and lock," referring to the two-pin twist-lock base design. The "10" denotes the distance in millimetres between the two pins. GU10 bulbs are known for their compact size and versatility, making them ideal for directional lighting in both residential and commercial settings. These bulbs are available in a variety of wattages and color temperatures, allowing users to customize their lighting experience to suit their needs. With their energy-efficient LED technology, GU10 bulbs offer long-lasting performance and significant energy savings compared to traditional incandescent bulbs, making them a popular choice for modern lighting installations.

Shop GU10 bulbs

The simplest way to check what size fitting you need is to look at the bulb you’re replacing. Most of them will include the fitting type somewhere on the underside of the bulb.

If you’re still uncertain, or simply want to explore the full range, click here to check out all our light bulbs.

E14 / E27 Bulb Fittings: Named after Edison, E14 and E27 fittings resemble screws, with E14 being thinner. Both are common for various lighting fixtures.

B22 Bulb Fittings: Featuring a bayonet cap base, B22 bulbs are secured with a twist and lock motion.

GU10 Bulb Fittings: Utilizing a twist and lock mechanism with two pins, GU10 bulbs are ideal for spotlights and downlights.

About the author

Jon Duffy is a Digital Merchandiser at Maplin.

An avid gamer from a young age, Jon has dabbled in gaming journalism and dedicates much of his spare time to this hobby. He also has an interest in music, playing bass guitar in a rock covers band.

Having previously worked as a copywriter with another electronics retailer, he was eager to join Maplin with their new online venture. In addition to writing blogs, Jon also works on many of the website's landing pages and adding new tech to the range.