How to choose LED bulbs: lumens and colour explained

By Saadat Rafiq · 2 min read · 5 steps · Updated 4 October 2026

Step pictures

3 of 5 steps, our drawings

Checked

October 2026

Sources

1, linked below

The figures on this page are from the Energy Saving Trust (last updated 28 August 2025). It puts the saving from replacing all the bulbs in a home with LEDs at 45 pounds a year in Great Britain and 55 pounds in Northern Ireland.

Step by step

1. Choose brightness in lumens

   To match an old incandescent bulb: 15 watt is 140 lumen, 35 watt 250 lumen, 40 watt 470 lumen, 60 watt 800 lumen, 75 watt 1,050 lumen and 100 watt 1,520 lumen.

   Done

2. Choose the colour of the light

   Very warm white, 2700K, has a similar tone to incandescent bulbs and suits living areas and bedrooms. Warm white, 2700 to 3000K, gives a warm and cosy glow and suits most general household lighting. Cool white, 4000 to 4500K, is a purer white that can be a bit harsh in most rooms; it might suit bathrooms and maybe kitchens.

   Done

3. Check the colour quality

   The colour rendering index (CRI) says how well colours show under the bulb. A CRI of 80 or more is good for most household tasks.

   Done

4. Check the dimmer

   Not all LED bulbs will work with a dimmer control, so check before buying.

   Done

5. Know what you save

   LEDs last up to 20 times longer than halogen bulbs in many cases. Replacing all bulbs with LEDs saves 45 pounds a year in Great Britain and 55 pounds in Northern Ireland.

   Done

Good to know

The pictures on this page are our own drawings, not photos. Every figure comes from the source below.

In short: 800 lumen replaces 60 watt, 1,520 lumen replaces 100 watt. Warm white 2700 to 3000K for living areas, cool white 4000 to 4500K for bathrooms. CRI 80 or more. Check dimmer compatibility.