When buying a bulb or light fitting, compare light colour separately from light output. Two products can use the same wattage yet differ in brightness or colour appearance.
What does each number mean?
Kelvin, written K, describes the appearance of white light. Lumens, written lm, describe visible light output. Watts, written W, describe electrical power consumption. A higher kelvin value does not mean more lumens, and wattage alone cannot establish brightness.
Common colours to compare
- 2700–3000K: warm white with a yellowish appearance. A useful starting point if you prefer a warm feel in a living room or bedroom.
- Around 4000K: between warm and cool white, often called neutral white. Try it if you want a less yellow appearance in a kitchen or workspace.
- Around 6500K: a cooler, bluish white, sometimes called daylight. Choose it if you prefer that appearance after seeing it in the room.
These are appearance choices, not compulsory rules for each room. Colour names vary between brands, so compare the kelvin number.
Try it with your room
If possible, test one unit before buying a large quantity. Look at it with the walls and furnishings at the time you normally use the room. Matching the kelvin values of nearby fittings helps create a similar appearance. Colour rendering, described by CRI, is a separate characteristic from colour temperature.
Check compatibility before ordering
- Bulb cap, such as E27, or the fitting's mounting method.
- Overall dimensions and recessed cutout dimensions separately.
- The exact model's lumen output and kelvin rating.
- Dimming support and compatibility with the control, if needed.
- Manufacturer approval for enclosed fittings or the intended location.
For selectable-colour products, check how the colour is changed. Colour selection does not establish dimming support. Use an electrician for wiring changes or installation of fixed light fittings.
Related categories: Lighting, Indoor Lighting.
Technical references
- FTC: lumens, watts and lighting-label information.
- U.S. Department of Energy: colour temperature, CRI, dimming and enclosed-fixture compatibility.
- Philips Lighting: examples of common colour temperatures for home lighting.
U.S. Department of Energy — Purchasing Energy-Efficient Light Bulbs
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