Comparing two colors numerically means converting both HEX values into D50 CIELAB coordinates and feeding them into the CIEDE2000 formula, which returns a single difference number called Delta E 2000. The formula adjusts the CIELAB a axis near neutral grays, weights lightness, chroma, and hue differences separately, and adds a rotation term that corrects a known weakness in older Delta E versions around the blue region. With default weights kL, kC, and kH all equal to one, the calculation is symmetric: comparing color A with color B gives the same result as comparing B with A to within floating-point display precision. Identical inputs always return zero, and larger numbers describe a greater formula-defined distance between the two color coordinates. The Color Difference Calculator performs exactly this conversion path on two opaque six-digit sRGB HEX values you paste in, runs the math in your browser, and prints the Delta E 2000 number alongside the D50 CIELAB coordinates that produced it. Everything stays on your device, and no color value is uploaded at any stage of the comparison.
What "Comparing Two Colors" Actually Means
Putting two swatches next to each other on a screen gives you a visual comparison, but that picture depends on the monitor you are looking at, the brightness in the room, and the way your eyes interpret adjacent color. A numerical comparison works differently: both HEX values are pushed through a fixed conversion path into a perceptual color space, and a single formula returns a reproducible distance number. That number is the Delta E 2000 output you see from the calculator, and it stays the same on every device, in every browser, for the same two inputs.
The CIELAB color space was designed so that equal numerical steps correspond roughly to equal perceived steps for the average human observer. CIEDE2000 builds on that idea but corrects several distortions left in earlier Delta E versions. The Sharma, Wu, and Dalal paper that introduced the formula weights lightness, chroma, and hue differences separately, adds a rotation term for the blue region of the color space, and handles hue angles that wrap across the zero-degree boundary. The implementation used by the calculator follows that paper and is checked against eight sign-sensitive reference pairs from the supplemental dataset, which means it is not merely returning identity cases correctly.
Two practical consequences follow from the formula's design. First, the calculation is deterministic and symmetric: the same pair in either order yields the same number, subject only to floating-point display precision. Second, the number carries meaning only when paired with viewing conditions and a tolerance chosen for the workflow at hand. A Delta E 2000 of three may pass brand review and fail a textile QA check, depending on the standards each field applies.
Inputs the Calculator Will and Will Not Accept
The calculator accepts a deliberately narrow input format so that the color space and opacity are always explicit. Both HEX values must include a leading hash, six hexadecimal digits, and no alpha channel. Anything else produces a validation error before any conversion runs, which keeps the comparison reproducible from the inputs alone.
| Format | Example | Accepted? |
|---|---|---|
| Opaque six-digit HEX | #1F6FEB | Yes |
| Three-digit shorthand | #1AB | No |
| Eight-digit HEX with alpha | #1F6FEB80 | No |
| CSS named color | crimson | No |
| display-p3 value | color(display-p3 0.1 0.4 0.9) | No |
| Empty or missing hash | 1F6FEB | No |
Rejecting those formats is not a limitation, it is a safeguard. Three-digit shorthand, alpha-bearing HEX, and named colors all hide a parsing or compositing decision that would change the meaning of the comparison. If transparency matters for your project, the correct workaround is to composite each translucent color over the same known background before comparing, because a translucent foreground is not one standalone opaque sRGB color and the calculator cannot infer the missing background for you.
Run the HEX-to-Delta-E Comparison in Your Browser
- Open the Color Difference Calculator in a current desktop or mobile browser. No account, extension, or download is required to start.
- Enter the first color as a six-digit HEX value with a leading hash, such as #1F6FEB, into the first input field.
- Enter the second color the same way in the second field, for example #0B5ED7.
- Select Compare colors to run the conversion and the CIEDE2000 calculation on both values locally in the browser.
- Read the Delta E 2000 result printed next to the two swatches, along with the D50 CIELAB coordinates (L*, a*, b*) used for each color.
- Copy the original HEX values, the Delta E 2000 number, and the tolerance or viewing context that applies to your workflow so the comparison can be reproduced later by anyone reviewing the result.
If you want a guided walkthrough written for first-time users, the Color Difference Calculator for Beginners: HEX to Delta E guide breaks the same flow into plain-English steps and shows what each field of the output means.
Inside the Conversion Path From HEX to Delta E 2000
The conversion follows the sample path described in the W3C CSS Color 4 specification. Each step is fixed and runs in the browser, so every comparison is reproducible from the same two HEX inputs alone.
| Stage | What happens |
|---|---|
| 1. Parse | Two opaque #RRGGBB HEX values are parsed into integer red, green, and blue channels in sRGB. |
| 2. Linearize | Each sRGB channel is normalized to a 0–1 range and pushed through the sRGB transfer function to remove gamma encoding. |
| 3. D65 XYZ | Linear sRGB is multiplied by the standard sRGB-to-XYZ matrix, producing CIE XYZ relative to the D65 illuminant. |
| 4. D50 adaptation | The D65 XYZ values are adapted to D50 with the Bradford chromatic-adaptation matrix. |
| 5. CIELAB | D50 XYZ is converted to CIELAB. Display values are rounded for readability, while unrounded numbers feed the next step. |
| 6. CIEDE2000 | Both CIELAB pairs are passed through the CIEDE2000 formula with kL, kC, and kH each equal to one, returning the Delta E 2000 number. |
Validation does not stop at the input box. The implementation is checked against eight sign-sensitive reference pairs from the Sharma, Wu, and Dalal supplemental dataset, so any future change to hue wrapping or weighting terms would break the verification rather than silently passing easy identity cases.
Reading the Delta E 2000 Number With Context
The Delta E 2000 number is reproducible, but it does not come with a universal pass or fail label. The calculator intentionally avoids calling any fixed value identical, acceptable, or rejected because perception depends on viewing conditions, display calibration, ambient light, surface texture, surrounding colors, observer vision, and the tolerance chosen for the workflow at hand.
What the number does give you is a comparable reference. Two color pairs that share a similar Delta E 2000 under the same comparison settings will look similarly different on the same calibrated display. That makes the value useful for documenting design-token revisions, QA notes for sampled image colors, and repeatable comparisons between palette revisions. Recording both HEX values, the reported number, and the workflow context is what turns a single calculation into something another person can verify later.
Different fields apply different acceptance limits. Brand review, photography, paint, textiles, printing, and interface design can each use different instruments and tolerances. Treat the calculator's output as a reproducible comparison aid that fits inside your own QA process, not as a replacement for that process.
What the Result Cannot Prove
The two swatches on the page give a quick visual reference, but a screen preview is not colorimetry evidence. Browser rendering, monitor gamut, color profiles, brightness, and calibration all change how the swatches look. The numeric calculation is based only on the entered sRGB coordinates and the documented conversion path, so it cannot measure a real object or infer a printer profile from those numbers.
That distinction is especially important for print and manufacturing. Proving that two physical samples match requires calibrated instruments and process-specific illuminant, observer, profile, substrate, and tolerance conditions. The calculator will tell you how close two HEX values are in CIELAB space, but it will not tell you how a pigment, a fabric, or a press run will reproduce them in practice.
The tool is also not an image picker, a spectrophotometer, an ICC profile converter, an accessibility contrast checker, or a certification service. For text readability, use a contrast-ratio tool that reports WCAG ratios. For physical manufacturing decisions, use the instruments and standards your process already requires.
For a deeper look, see Delta E Calculator: A Standards-Based CIEDE2000 Walkthrough.