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.

What is the Color Temperature to RGB Converter?

Convert a blackbody color temperature from 1000K to 40000K into approximate sRGB and hex, with a live swatch and presets for candlelight, daylight, and blue sky. Useful for lighting, white-balance, and shader work. Runs in your browser. It runs free in your browser on Gera Tools, with nothing uploaded.

Color Temperature to RGB Converter

Name: Color Temperature to RGB Converter
Creator: Gera Tools
License: https://creativecommons.org/licenses/by/4.0/

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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.

Common reference temperatures and their RGB

The presets in the tool cover the most useful benchmarks, but it helps to understand why these temperatures matter:

Source	Temperature	Character
Candlelight	~1800K	Deep amber-orange
Incandescent bulb	~2700K	Warm orange-white
Warm white LED	~3000K	Soft white
Neutral white	~4000K	Clean white
D50 (print reference)	5000K	Slightly warm white
D65 (sRGB white point)	6500K	Near-neutral white
Overcast sky	~7000K	Cool blue-white
Clear blue sky	~10000K+	Distinctly blue

The D65 reference at 6500K is the white point sRGB monitors are calibrated to, which is why it converts to an almost perfectly equal RGB value.

Worked example

For a 2700K incandescent bulb the conversion yields roughly rgb(255, 169, 87) — orange-tinted and clearly warm. At 6500K (D65 daylight) you get approximately rgb(255, 249, 253), which is near-white with just a trace of blue. At 10000K the blue channel dominates visibly: roughly rgb(202, 218, 255).

Where to use this in practice

UI and game lighting: when you are building a day-night cycle or an indoor scene, the Kelvin temperature of each light source maps directly to the tint you add to that light’s color. Converting at 2700K gives you the exact RGB to apply to a lamp emitter.

White balance overlays: photographers and video editors who build custom LUTs or correction filters can use this to find the raw RGB of a white card under a given light source, which anchors their neutral point.

Shader constants: in GLSL or HLSL you sometimes need a hard-coded color for a sky or sun at a known physical temperature. Copy the hex from this tool directly into your shader as the light color.

Remember the inverted convention: a bulb marketed as “warm white” at 2700K is physically cooler than 6500K daylight. The warmer the visual appearance, the lower the Kelvin number — the opposite of everyday temperature language.