Traditionally we’ve measured the strength of our lightbulbs (lamps) in watts. A 40-watt incandescent light bulb was dim, a 100–watt one was bright. However, that measure was misleading. Watts are a measure of power consumption, not of light.
Lumens are a measure of the light given out by a lamp. The higher the lumens, the brighter the lamp.
A traditional 40-watt bulb is equivalent to a 470 lumen LED bulb. And a traditional 100-watt bulb is equivalent to a 1,520 lumen LED bulb.
The colour of light is measured in degrees Kelvin. The colour is what results in us perceiving light as warm or cold; harsh or soft. Cold light will have more blue in it and warm white has more yellow.
Daylight is 5,000 Kelvin
Cool white is 4,200k
Warm white is 2,700k
We suggest you test one bulb to make sure you’re happy with the light it gives before investing in larger quantities.
There is also another colour measurement, the colour rendering index or CRI. This measures the quality of a light source compared with sunlight. Sunlight is given the maximum CRI value of 100. The closer a lamp is to that, the better its ability to show true colours. This is important in art galleries and shops, but is not critical for optimal light levels in homes. A CRI of 80 or more is appropriate for most household tasks. The bulb’s packaging will indicate the CRI alongside the lumen value.