How is the Kelvin-to-RGB colour calculated?

It uses Tanner Helland's widely-cited black-body radiator approximation, which is accurate enough for white-balance, lighting and LED reference between roughly 1000 K and 40000 K.

What Kelvin value is warm white versus cool white?

Warm white is roughly 2700–3000 K (orange-tinted, like a soft incandescent bulb), neutral white is around 4000 K, and cool or daylight white is 5000–6500 K (bluish). Above 6500 K light looks distinctly blue.

Why does a higher Kelvin look bluer, not hotter?

It is counterintuitive, but a hotter black-body radiator emits more blue light. So low Kelvin appears warm/orange and high Kelvin appears cool/blue — the opposite of the everyday "warm/cool" sense of temperature.

Is anything sent to a server?

No — the conversion runs entirely in your browser and nothing is uploaded.

What is the Color Temperature Converter (Kelvin to RGB)?

Convert a colour temperature in Kelvin to an approximate sRGB hex and RGB value using the black-body approximation. Free, instant, and runs entirely in your browser — nothing is uploaded. It runs free in your browser on Gera Tools, with nothing uploaded.

Color Temperature Converter (Kelvin to RGB)

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

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Colour temperature describes the colour of a light source on the Kelvin (K) scale. Low values around 1900 K look warm and orange, like candlelight, while high values of 6500 K and up look cool and blue, like overcast daylight. This converter maps any Kelvin value to an approximate sRGB colour (hex and RGB) with a live swatch, so you can preview a white-balance, bulb or LED temperature on screen.

How it works

The tool uses Tanner Helland’s widely-cited black-body approximation, valid from roughly 1000 K to 40000 K. It divides the Kelvin value by 100, then applies separate piecewise formulas to each channel:

Red is full (255) up to 6600 K, then falls off via a power curve.
Green rises logarithmically below 6600 K and falls off above it.
Blue is 0 below 1900 K, rises logarithmically in the mid range, and is full above 6600 K.

Each channel is clamped to 0–255. The result is a visual approximation of how a black-body radiator at that temperature appears on an sRGB screen — not a calibrated colorimetric value.

Common Kelvin reference points

Kelvin	Appearance	Typical source
1900 K	Deep warm orange	Candle flame
2700 K	Soft warm white	Classic incandescent bulb
3000 K	Warm white	Halogen, warm LED
4000 K	Neutral white	Cool white fluorescent
5500 K	Daylight	Midday sun
6500 K	Bright daylight	sRGB reference white
10000 K	Cool blue	Blue sky / shade

So entering 6500 K produces a near-white swatch, while 1900 K produces a warm orange one. It runs entirely in your browser — nothing is uploaded.

Where this is useful

Photography and video white balance — camera white balance is set in Kelvin. If your image looks too orange under indoor lighting (around 2700–3200 K), you set white balance higher, toward 5500 K, to neutralise it. The swatch gives a quick visual reference for any value you are considering.

LED bulb selection — residential LEDs are labelled “2700 K”, “3000 K” or “4000 K” on the box. Preview each in the converter to understand the visual difference before buying, particularly when mixing bulbs in the same room.

Studio lighting — film and photo studios balance artificial lights at a consistent Kelvin to ensure accurate skin tones. Daylight-balanced studio lights typically run at 5600 K; tungsten at 3200 K.

UI design and dark mode — blue-light filter features like Night Shift shift the screen white point toward 3000 K or lower. This converter lets you see what that shift looks like on a neutral swatch, which is useful when checking whether a dark-mode colour palette still reads well under warm filtering.