The CRI, colour rendering index
The technical criterion everyone ignores, which changes everything
A cheap LED can display a beautiful shade on the box and betray all your colours once installed. The CRI is the indicator that makes the difference.
§ 01The principle
The CRI (Colour Rendering Index), also called IRC in French, measures the ability of a light source to faithfully reproduce the colours of the objects it illuminates. The scale runs from 0 to 100. Daylight, the absolute reference, is 100. A good residential LED must be at least 80. A precision LED (kitchen, dressing room, bathroom mirror) must be 90 or above.
The problem: the vast majority of cheap LEDs run between 70 and 80. With such a source, your favourite colours (the green of your sofa, the burgundy of your curtains, the colour of the meat on your plate) will appear dull, greyish, false. You chose your colours in natural light (CRI 100) and you are looking at them under CRI 75. A guaranteed mismatch.
It is one of the most important technical criteria in lighting, and one of the least known to the general public.
CRI 80 minimum · CRI 90 for precision · CRI 95 for colour-critical work
On the box, look for "Ra" or "CRI" followed by a number. Below 80, avoid.
§ 02Putting it into practice
Where to find the CRI. On the bulb box, in the technical specifications. The information appears under one of these names: "Ra", "CRI", sometimes followed by the figure. If you cannot find it on the box, that is a bad sign: reputable manufacturers always display it. Philips, Osram, Tala, Plumen, Soraa, Tridonic mention it systematically.
Which CRI to target, by room.
CRI 80, sufficient for transit spaces. Hallway, entrance, dressing room, staircase, garage. Where you do not distinguish colours finely, 80 will do.
CRI 90, recommended for living spaces. Living room, bedroom, dining room, study. Your favourite colours (rug, sofa, framed artworks) deserve light that respects them.
CRI 95 or above, essential for precision spaces. Kitchen (worktop), bathroom (mirror), dressing room (choosing clothes). At 90 you perceive colours correctly, but at 95 you see them as in daylight. For applying makeup, choosing a tie or cooking, it is a clear qualitative step.
The trap to avoid. Ultra-cheap LEDs (£1 to £2) often run at CRI 70 or less. Apparent economy, but mediocre light. Better to invest in 5-6 bulbs at £8-15 each than to scatter a budget across 20 bulbs at £2.
- 01Check the CRI before every bulb purchase
- 02Aim for CRI 90 minimum in living spaces
- 03Push to CRI 95 for kitchen, bathroom and dressing room
- 04Invest in reputable brands (Philips, Osram, Tala, Plumen, Soraa)
- 01Buying bulbs without a CRI mention on the box
- 02LEDs at £1 per pack, often at CRI 70
- 03Low CRI LEDs in a kitchen
- 04Believing "a warm white bulb" suffices without checking the rendering
§ 03Professional variations
Photography studios work at CRI 98 minimum, it is the condition for photographed colours to be accurate. Part of this requirement is now migrating into high-end residential, especially in home chef kitchens and artists' studios.
The brand Soraa, specialist in high-CRI LED, is a reference among interior designers. Their CRI 95 bulbs with a high R9 rating (R9 specifically measures the rendering of reds, often ignored by cheap LEDs) have become a standard in prestige projects.
Pierre Yovanovitch systematically specifies CRI 90 or above in his specifications, to ensure that patinated woods, leathers, and natural weavings retain their colour richness in artificial light.
A bulb without a CRI rating is a bulb that makes no promise about your colours.
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