Light Color Temperature Converter

Color temperature measures the hue of a light source, expressed in Kelvin (K). Lower Kelvin values produce warm, yellowish light, while higher values produce cool, bluish-white light.

How color temperature works: The scale is based on the color of light emitted by a theoretical “black body” heated to different temperatures. At lower temperatures, the object glows red/orange (like a candle flame). At higher temperatures, it shifts through white to bluish-white (like bright daylight).

Color temperature reference chart:

Choosing the right color temperature for your space:

• Bedrooms and living rooms: 2,700-3,000K creates a cozy, relaxing atmosphere similar to traditional incandescent bulbs.
• Kitchens and bathrooms: 3,000-4,000K gives enough clarity for tasks while remaining comfortable.
• Offices and workspaces: 4,000-5,000K promotes alertness and concentration without feeling harsh.
• Garages and workshops: 5,000-6,500K provides bright, detailed visibility for precision work.

Practical tips:

• The CRI (Color Rendering Index) is separate from color temperature. CRI measures how accurately colors appear under a light. Look for CRI 90+ for living spaces.
• Mixing color temperatures in the same room can look unnatural. Keep all bulbs within 300K of each other.
• “Warm” and “cool” in lighting terminology are the opposite of color wheel terminology: warm light is yellowish, cool light is bluish.
• Tunable white or “smart” bulbs let you adjust color temperature throughout the day, from warm in the evening to cool during work hours.

Mireds, and why 300K is not always 300K

That “keep bulbs within 300K” rule has a catch, and it is the reason photographers use a different unit altogether. The eye responds to the reciprocal of color temperature, not to the temperature itself. The gap between 2,700K and 3,000K is plainly visible side by side; the gap between 6,200K and 6,500K, the same 300K on paper, is almost impossible to see.

The unit that fixes this is the mired (micro reciprocal degree), sometimes written MK⁻¹:

mired = 1,000,000 / Kelvin

On the mired scale, equal steps look like equal changes. 2,700K is 370 mireds and 3,000K is 333, a shift of 37. But 6,200K is 161 mireds and 6,500K is 154, a shift of only 7. Roughly five times less visible, which matches what your eye tells you.

A shift of about 10 mireds is the smallest most people notice, and photographic filters are sold by their mired shift for exactly this reason: an 80A blue filter is -131 mireds whatever you point it at. If you are matching bulbs in one room, compare their mired figures rather than their Kelvin figures and the “within 300K” rule stops misleading you at the cool end.