What is blackbody color temperature?

It is the temperature, in Kelvin, of an idealized glowing object whose emitted light matches a given color. Low temperatures near 2000K glow orange like a candle, while high temperatures near 10000K appear cool and blue, the opposite of everyday warm and cool language.

How accurate is this conversion?

It uses Tanner Helland's well-known polynomial approximation, which tracks the Planckian locus closely enough for UI, lighting design, and shader work. It is an approximation, not a spectrally exact computation, and is most accurate in the 1000K to 40000K range.

Why do higher temperatures look blue, not red?

Physically hotter blackbodies emit more energy at shorter, bluer wavelengths. The familiar warm and cool labels in photography are reversed from the physics, so 2700K bulbs are called warm white even though they are physically cooler than 6500K daylight.

What temperature is neutral white?

Around 6500K, the D65 daylight standard, which is the white point sRGB and most monitors are calibrated to. It converts to a near-equal RGB value. Common warm-white indoor bulbs sit near 2700K to 3000K.

Can I convert RGB back to a temperature?

Not uniquely, because most RGB colors do not lie exactly on the blackbody curve. You can only find a correlated color temperature, the nearest point on the locus. This tool runs the conversion in one direction, from Kelvin to RGB.

Color Temperature to RGB Converter

Convert color temperature to RGB

Color temperature describes the hue of a light source on a warm-to-cool scale measured in Kelvin. This converter turns any blackbody temperature from 1000K to 40000K into an approximate sRGB and hex color, with a live swatch so you can preview the shift from orange candlelight through neutral daylight to deep blue sky. It is handy for lighting UIs, white-balance previews, and shader constants.

How it works

The tool implements Tanner Helland’s piecewise approximation of the Planckian locus. The Kelvin value is divided by 100, then each channel is computed from logarithmic and power curves fitted to measured blackbody data. Below about 6600K the red channel is pinned at 255 and blue is computed from a log curve; above it red falls off as a power curve while blue saturates. Every channel is finally clamped to the 0–255 range. The result is the color the light source appears, not the color of an object lit by it.

Example and tips

A 2700K incandescent bulb converts to a warm rgb(255, 169, 87), while 6500K daylight lands near a neutral rgb(255, 249, 253). Remember the photography convention is inverted from the physics: bulbs sold as warm white are at lower Kelvin numbers. Use the presets to anchor common references, and treat the output as a perceptual approximation suitable for design rather than a calibrated photometric value.