How many lumens do you need for warm white light?

For warm white light you work with the same lumen figures as for neutral white, but in practice you need slightly more of them. Your eyes perceive warm light as less bright, so what adds up on paper quickly feels a little dark in the room.

Lumens and color temperature are independent

Two 400-lumen spots, one at 2700K and one at 4000K, give exactly the same amount of light. A light meter sees no difference. Yet you will describe the warm one as softer and the cool one as brighter.

That is because your eye is more sensitive to the green-blue part of the spectrum, and warm light simply contains less of it. The result is a systematic underestimate: choose 2700K and calculate tightly, and you end up too low.

The correction in practice

The usual rules of thumb are roughly 100 to 150 lumens per square meter for a living room and 200 to 300 for a kitchen or bathroom. If you are going for 2700K, take the top of those ranges rather than the average.

For a living room of 30 m² that puts you at around 4,500 lumens instead of 3,000. With 400-lumen spots that is a difference of about four spots, or one step up in spot.

What our warm spots give each

These spots can do 2700K or lower, with their light output alongside:

• Vigo — 320 lm, Dim2Warm from 3000K down to 2000K
• Marlo — 350 lm, CCT with 2700K as its lowest setting
• Lesto — up to 400 lm, CCT, wattage switch 4 or 6 watts
• Quaro — 400 lm, CCT
• Lyvo — 500 lm at 5 watts, 700 lm at 7 watts
• Ferro — 600 lm, CCT up to 5700K

If you are going warm and have a large space, the Lyvo on its high setting or the Ferro is the logical choice. With the 320-lumen Vigo you need almost twice as many spots for the same result.

Dim2Warm changes the sum

With a Dim2Warm spot the color temperature drops as you dim. So at full power you have the brighter 3000K and the full light output, and it only turns warm as you turn it down — exactly when you want less light anyway.

That means you can work with the normal rule of thumb for Dim2Warm. You handle the correction for warm light with the dimmer instead of with extra spots. For a living room that is the neatest solution, provided you use a suitable dimmer.

Do not count the ceiling alone

The rule of thumb covers all the light in the room. A reading lamp, a pendant above the table and wall lights all count. With warm light that spread matters even more than with neutral white: several small warm light sources feel more pleasant than one ceiling lighting everything equally hard.

So aim for about two thirds of your total in ceiling spots and fill in the rest with separate fixtures.

Choose your color before you start counting

The order helps: settle your color temperature per room first, work out the number of lumens next, and only then choose the spot. Do it the other way round and the lovely spot you picked turns out to give just a little too little light.

More about the settings themselves in What light color is 3000K?, and the full range is in the recessed spotlights.