How to Choose Light Bulbs: Lumens, Kelvin, CRI and Dimming
Updated: Oct 7
The fitting gives a room its shape and character; the lamps inside it help determine the finished effect. A bulb that fits the holder can still give you the wrong brightness, colour or atmosphere. Before buying a set, discuss how you want the room to feel and how you use it.
At Illuminations of Camberley, we can help you choose suitable lamps — what most people call light bulbs — when you collect your fitting. Tell us in advance if you need a particular lamp or quantity so we can check options, prices and availability.
Start with the fitting and the room
Have the fitting’s product reference and manufacturer’s instructions to hand. Check the specified lamp type, physical size and permitted wattage. For an existing light, bring its details or a photograph of the bulb and holder. An integrated LED fitting needs its own product-specific advice rather than a conventional replacement bulb.
Next, tell us what the light needs to do: soften a sitting room, illuminate a dining table, support reading or complement other lights. Photos of the room, its finishes and any existing lighting help us suggest a sensible starting point.
Lumens: choose the light output
Lumens describe light output. Think about how much light you need from the whole fitting, especially when it takes several lamps. Shades, glass and direction also affect the result, so choose brightness for the room rather than the bulb alone.
Wattage: power use and the fitting’s limits
Watts measure electrical power, not brightness. Compare LED light output in lumens and follow the fitting’s actual wattage limits; an old-style ‘equivalent wattage’ is a brightness comparison, not its power consumption.
Kelvin: choose warm or cooler light
Kelvin describes the colour appearance of white light. 2700–3000K is a common starting point for domestic rooms; around 4000K gives a cooler appearance. Your finishes and preference matter. A higher Kelvin number does not mean more brightness.
CRI: consider the colours in your room
CRI describes colour rendering. Higher values generally indicate more faithful colour appearance, with 80 or above a common household starting point. It is one measure of light quality, so consider it alongside the other specifications.
Tell us if showing artwork, fabrics or decorative finishes well is particularly important. Choosing the fitting and its lamps together gives us a clearer picture of the effect you are trying to achieve.
Dimmable: check the complete combination
A dimmable LED needs a compatible dimmer. Give us the dimmer details and ask your electrician to confirm the combination and load. ‘Dimmable’ on the packaging does not promise compatibility with every control.
Appearance matters too
If the bulb is visible, its shape and finish become part of the design. Discuss whether you want the lamp itself to stand out or let the glass and metalwork take the attention. Check the physical fit and manufacturer’s requirements before choosing on appearance.
Choose your lamps when you collect
You do not need to settle every specification on your own. Bring your order confirmation, room photo and dimmer details to collection. We can discuss suitable options and their prices, then you can buy the lamps with your fitting. Contact us beforehand to check availability if you need everything for a particular installation date.
Visit Illuminations of Camberley, 66–68 High Street, Camberley, GU15 3RS. Open Monday–Saturday, 9am–5:30pm; closed Sundays and Bank Holidays. Online fitting orders are for collection only. Call 01276 24941 or email sales@illuminations.uk.com.
Further reading
Our practical selection advice is informed by showroom experience. For consumer explanations of lumens, wattage, colour temperature, CRI and dimming, see the Energy Saving Trust guide below. Always check the specifications for your particular fitting, lamps and controls.
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