Light Bulb Sizes: A Guide to Choosing the Right Bulb

28 February 2024

Whatever your lighting need, there is a bulb to fill it. The first big choice when picking a bulb is whether to go smart, or old-fashioned. Smart bulbs are more expensive initially than traditional bulbs, but they save you money in the long-run as they last a very long time, are more energy efficient and are also environmentally sound. They are also significantly more versatile. 

• There is a variety of apps that make everything to do with lighting customisable.
• You can switch on all or specific lights in your house with one click.
• Colour and temperature of light in each room can be changed as often as you want.
• You can set routines to have certain types of lighting at different times.
• Lights can be turned on remotely or set with a timer, to keep your house looking occupied even when you’re away.
• You can link your TV to the lighting so that the image spreads over your walls in real-time.
• They can be voice-activated with Amazon Alexa, Google or Apple.

As a general guide with smart bulbs, wattage is no longer an important metric, and instead brightness is measured in lumens. All smart bulbs will have a label stating their lumens, colour, lifespan, energy usage and cost for a year - allowing you to compare bulbs and find the right one for you.
Meet the smart led bulbs from Philips Hue.

All light bulb caps and base fittings are labelled with a code consisting of letters and numbers. Before buying a new bulb, look at the existing bulb in the light fitting to ensure you purchase the right size and type of bulb for your specific need.
The first letter of the code tells you the base or cap type of the bulb - for example, Bayonet Cap or Edison Screw Base.
The numbers (in millimetres) tell you the diameter of the base, or the distance between the pins - for example B22, E27 or GU10

Tip: It is important to note whether your light fitting takes screw or bayonet type bulbs, as these are not interchangeable.

B22 Bayonet Bulbs

This is one of the most common bases for 'Type A light bulbs' in the U.K. A bayonet fitting bulb has 2 pins that stick out of the side, and has a base diameter of 22 mm.

If you have bayonet light fittings and want smart bulbs that can change colour temperature, then the B22 bulb from Philips Hue is a good option. This bulb gives you both warm white and coloured light, is dimmable and can be controlled with the Hue app or voice-activated platforms. This bulb is equivalent to 60W; they’re predicted to last 25,000 hours and guaranteed for two years. The lumen output is 806lm @4,000 K. The same bulb is also available in warm white.

If you have bayonet light fittings and want smart bulbs that can change colour temperature, then the B22 bulb from Philips Hue is a good option. This bulb gives you both warm white and coloured light, is dimmable and can be controlled with the Hue app or voice-activated platforms. This bulb is equivalent to 60W; they’re predicted to last 25,000 hours and guaranteed for two years. The lumen output is 806lm @4,000 K. The same bulb is also available in warm white.

This is another most commonly seen base fitting in the U.K. It is easy to screw into the socket of a light fixture. 

Philips Hue E27 bulbs vary in specification. There is a white bulb, which allows you to have warm or cool white light and is dimmable. And, there’s a dual pack of Hue White and colour ambiance. These bulbs are more fun in terms of the range of colours they offer. Just like the B22 smart bulbs from Philips Hue, The E27 bulbs are equivalent to 60W, predicted to last 25,000 hours, and guaranteed for two years.

These are just the smaller form of the E27, and in a different shape. If your light fitting is for a candle type bulb with a screw-in fitting, then the E14 may work for you. Some wall lights, lamps and chandelier style lights hold this type of bulb - also known as Type B light bulbs. 

Philips Hue candle bulbs are dimmable and can be controlled with the Hue Bridge or voice activation. These are equivalent to 40W, last 25,000 hours, and have a guarantee of two years.

These bulbs have two little prongs under them and are often used for ceiling-lights in kitchens and bathrooms, as they nestle into the ceiling and the light fitting is then flush. 

Philips Hue sells these bulbs in a single or a dual pack. You can choose the ones that give warm to cool white light or go for the white and coloured range. They are dimmable and can be controlled with the Hue Bridge or voice activation.

See the full range of Philips Hue GU10 bulbs.

Whatever your need and whichever room you’re in, remember to carefully check the size and style of the light fitting you’re working with. By checking thoroughly, you won’t suffer the disappointment and inconvenience of purchasing the incorrect size.