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Color Luminance Calculator
ColorCalculate relative luminance of any color for WCAG contrast ratio compliance.
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Color Luminance Calculator
Calculate relative luminance and perceived brightness of a color
Preset Colors
Relative Luminance0.000000
Luminance %0.00%
Perceived Brightness
Color Values
HEX
#3498DB
RGB
52, 152, 219
HSL
204°, 70%, 53%
Lightness Scale Preview
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Your color:
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Contrast Helper
For text to be readable, use luminance contrast of at least 4.5:1 (AA) or 7:1 (AAA)
T
White background: 21.00:1T
Black background: 1.00:1Formula Used
L = 0.2126 × Rs + 0.7152 × Gs + 0.0722 × Bs
Where Rs, Gs, Bs are the linearized sRGB values:
if (C ≤ 0.03928) then Cs = C / 12.92 else Cs = ((C + 0.055) / 1.055)2.4
Quick answers for Color Luminance Calculator
What does the Color Luminance Calculator do?
Calculate relative luminance of any color for WCAG contrast ratio compliance. The Color Luminance Calculator is one of 900+ free developer tools on Toolblip - all open to use without a signup.
How do I use the Color Luminance Calculator?
Open the Color Luminance Calculator on this page, paste or upload your input, and the result updates as you type. Use the copy button to grab the output, or adjust options to tune the result. Nothing you enter leaves your browser.
Is the Color Luminance Calculator free to use?
Yes. The Color Luminance Calculator is a free online tool on Toolblip - no signup, no account, no hidden usage limits. It runs in your browser and works on desktop and mobile.
Is the Color Luminance Calculator safe and private?
Yes. The Color Luminance Calculator processes your data entirely client-side, so nothing you paste is uploaded or stored on any server. It's safe to use with internal snippets, private keys for debugging, or any other sensitive content you'd rather not send to a remote service.
What color formats does the Color Luminance Calculator support?
The Color Luminance Calculator works with the formats web developers reach for every day - HEX, RGB / RGBA, and HSL. You can copy any value with one click for use in CSS, design tools, or code.
Can I use the Color Luminance Calculator offline?
Once the page has loaded, the Color Luminance Calculator continues to work without an internet connection. Bookmark this page and return to it anytime - all logic runs locally.