Lab to LCH converter
A direct geometric conversion that does not depend on the white point, useful for reading measurement reports or tuning gradients.
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Processing and privacy: The result is calculated inside your browser and your data is not sent to any server.
How to use it
- Enter lightness l*, a* axis and b* axis.
- The result appears straight away and updates as you edit.
- Copy the result, or copy a link that keeps the same values to share it.
How it is calculated
C = √(a² + b²), h = atan2(b, a) in degrees from 0 to 360.
Example
Inputs: Lightness L* = 60.18, a* axis = 62.06, b* axis = 54.33. Result: LCH values: L* 60.18, C* 82.48, h 41.2°; Lightness L*: 60.18; Chroma C*: 82.4815.
Limits and caveats
- When a* and b* are both zero the hue is undefined and shows as 0°.
Questions about this tool
Does the conversion change the color?
No. L* stays the same, and C* and h describe the same point in polar rather than Cartesian form.
Do I need to choose D65 or D50?
No, it is pure geometry. The white stays whatever your Lab values were based on.
How is the angle found in every quadrant?
We use atan2, which accounts for the signs of a* and b*, and add 360 to negative results so h stays between 0 and 360.