LCH to LAB Converter
Convert CIELCH values (lightness, chroma, hue angle) back to rectangular CIELAB a* and b* coordinates. Use it to turn an adjusted chroma or hue into LAB values.
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What is LCH to LAB Converter?
The LCH to LAB Converter turns CIELCH values into CIELAB. Enter lightness L*, chroma C*, and hue angle h in degrees, then read L*, a*, and b* with a color preview. The tool converts polar coordinates on the color plane back to rectangular ones.
How does LCH to LAB Converter work?
CIELCH describes the same colors as CIELAB in polar form. L* is lightness, C* is the distance from the neutral axis, and h is the angle around it. Converting back uses a* = C* cos(h) and b* = C* sin(h), with h taken in degrees, while L* passes through unchanged.
Values use the D65 white point. The preview swatch renders the color as sRGB through XYZ, and colors outside the sRGB gamut are clamped for display only. The LAB numbers themselves are not clamped.
Key Features
- Computes a* = C* cos(h) and b* = C* sin(h)
- Takes hue as an angle in degrees from 0 to 360
- Chroma slider runs from 0 to 150
- Passes lightness L* through unchanged
- Live sRGB preview of the input color
- Four preset colors with matching LCH values
Common Use Cases
Turn an adjusted chroma into LAB
Scale chroma or rotate hue in LCH, then convert the result back to a* and b* for a LAB-based tool.
Check a palette generator
Compare a generator's LAB output against the LAB values calculated from its LCH settings.
Prepare input for a Delta E calculation
Delta E formulas take L*a*b*, so convert LCH measurements first.
Verify trigonometry code
Compare your own cosine and sine implementation against a reference result.
How to Use This Tool
Enter L*, C*, and h
Use the sliders or type values. L* runs from 0 to 100, C* from 0 to 150, and h from 0 to 360 degrees.
Check the preview
The swatch shows the color as sRGB so you can see what the values describe.
Read a* and b*
The result card lists L*, a*, and b* to two decimal places.
Copy the LAB string
Copy the lab() value into your notes or code.
Pro Tips
- 1
A hue of 0 degrees points toward +a*, and 90 degrees points toward +b*. The angle increases from red-magenta toward yellow.
- 2
Chroma 0 gives a neutral gray, and hue has no effect there.
- 3
Values are D65 LAB. CSS lab() and lch() use a D50 white point, so numbers will not match those functions.
- 4
Chroma above about 134 lies outside sRGB, so the swatch is clamped even when the LAB values are valid.
- 5
Round-trip a value through the LAB to LCH Converter to confirm your hue angle.
Frequently Asked Questions
How do you convert LCH to LAB?
Keep L* unchanged, then calculate a* as C* times the cosine of the hue angle and b* as C* times the sine. This tool applies those formulas for you.
What LAB does LCH 55.63, 66.77, 285.23 give?
It gives about L* 55.63, a* 17.54, and b* -64.42, which is the Tailwind blue-500 color.
What range does the hue angle use?
Hue runs from 0 to 360 degrees, starting at +a* and increasing toward +b*.
Why are my values different from CSS lch()?
CSS color functions use a D50 white point. This converter uses D65, so the same numbers describe slightly different colors.
Can chroma be negative?
No. Chroma is a distance from the neutral axis, so it starts at 0. A negative a* or b* shows up as a hue angle instead.
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