Compare Two Colors
Compare any two colors side-by-side: enter HEX values, pick Pantone codes from the dropdown, or use the color pickers. The tool shows the perceptual difference in Delta E 2000, the WCAG contrast ratio for text, and the AA/AAA accessibility verdicts. All calculations run live in your browser.
What this comparison tool does
Designers compare colors for two reasons: to see how similar two colors are (perceptual difference), and to check whether one color is readable on another (accessibility). These are different measurements and this tool shows both. Delta E 2000 answers the first: it is a perceptual difference score with a consistent scale — under 1 is imperceptible, under 5 is close but noticeable, and higher values mean increasingly distinct colors. WCAG contrast answers the second: it is a ratio between 1:1 and 21:1 that measures how readable text of one color will be on a background of another color.
Both values are computed from the same underlying RGB values but through different formulas: Delta E 2000 operates in CIELAB and weights the differences by human perceptual sensitivity, while WCAG contrast operates on relative luminance (a weighted sum of linearized RGB channels) and is specifically tuned for readability. A high Delta E does not imply good contrast — two very different hues can have the same luminance and fail AA — and a high contrast does not imply a good match.
Understanding ΔE 2000
Delta E 2000 (written ΔE00) is the current CIE standard for perceptual color difference. It operates in CIELAB — a color space designed to be perceptually uniform — and adjusts for the fact that the human eye is more sensitive to differences in some hue regions than others. The formula is complex but the interpretation is straightforward:
| ΔE 2000 | Meaning |
|---|---|
| < 1.0 | Imperceptible — most people cannot tell the two colors apart |
| 1.0 – 2.0 | Very close — trained observers notice, casual viewers may not |
| 2.0 – 5.0 | Close — clearly different but visually related |
| 5.0 – 10.0 | Noticeably different — different families, related mood |
| 10.0 – 30.0 | Distinct — clearly different colors |
| > 30.0 | Completely different — no perceptual relationship |
Understanding WCAG contrast
The WCAG contrast ratio is defined by the Web Content Accessibility Guidelines as (L1 + 0.05) / (L2 + 0.05), where L1 is the relative luminance of the lighter color and L2 is the relative luminance of the darker color. Relative luminance is computed from the sRGB channels using the standard formula: linearize each channel with the sRGB transfer function, then combine with weights 0.2126 (R), 0.7152 (G), 0.0722 (B). The result is a ratio between 1:1 (identical colors) and 21:1 (pure black on pure white).
WCAG defines two conformance levels for text: AA (4.5:1 for normal text, 3:1 for large text at 18pt+ or 14pt+ bold) and AAA (7:1 for normal text, 4.5:1 for large text). Most organizations target AA as the minimum for public content and AAA for critical information. This tool shows all four thresholds so you can see exactly where your pair sits.
How the calculations work
Both colors are first converted to RGB (from the HEX input, the color picker, or the Pantone selection). Delta E 2000 then operates in LAB space: RGB → XYZ → LAB, then the standard ΔE00 formula produces a single number. Contrast ratio operates on relative luminance: RGB → linear RGB (via the sRGB gamma curve) → weighted sum. The two formulas share the RGB → XYZ → LAB pipeline for ΔE, and the RGB → linear-RGB pipeline for contrast, but they never interact — each produces an independent measurement.
Use cases
- Accessibility auditing. Check whether text color and background color pass WCAG AA or AAA before shipping a design.
- Brand color decisions. Compare two candidate brand colors to see how perceptually distinct they are — useful for choosing between similar candidates.
- Quality control. Compare a target Pantone code with the color actually measured from a proof (via HEX input) to see the perceptual delta.
- Color palette design. Check that all pairings in a palette maintain good contrast for UI components like buttons and form labels.
- Print proofing. Compare the Pantone code from a print spec against the color rendered by a mockup or proof.
Common mistakes
- Confusing ΔE and WCAG contrast — they measure different things. A high ΔE does not mean good contrast, and vice versa.
- Checking contrast only for normal text — large text (18pt+ or 14pt+ bold) has lower thresholds and often passes where body text would fail.
- Forgetting that WCAG contrast applies to text on background, not color on color — a red on green pairing may fail WCAG contrast but still be visually legible for a logo or illustration.
- Trusting the screen for print decisions — use physical chips for print, and treat both ΔE and contrast as design-time measurements, not print specifications.
- Assuming a ΔE under 2 makes two colors interchangeable — for brand work, even small perceptual differences matter if they cross a name or code boundary.
Frequently asked questions
How do I compare two colors with this tool?
Enter a HEX value, pick a Pantone color from the dropdown, or use the color picker for each of the two panels. The tool updates live: it shows the exact difference between the two colors in Delta E 2000 (perceptual color difference), the WCAG contrast ratio for text, and the AA/AAA accessibility pass/fail verdicts. You can also load any two Pantone codes for a design hand-off.
What does the ΔE 2000 value mean?
Delta E 2000 measures perceptual color difference. A value under 1 means the two colors are essentially indistinguishable to the human eye; under 2 means very close; under 5 means close but distinguishable; over 10 means only loosely related; and roughly 30 or higher is a completely different color. It is the current CIE standard and is more accurate than older Delta E 1976.
What is WCAG contrast and why does it matter?
WCAG (Web Content Accessibility Guidelines) defines a contrast ratio between text and its background. WCAG AA requires a contrast ratio of at least 4.5:1 for normal text and 3:1 for large text (18pt+ or 14pt+ bold). AAA requires 7:1 and 4.5:1 respectively. The ratio is computed from relative luminance, which itself is derived from the RGB channels with the sRGB gamma curve applied. Higher ratios mean the text is easier to read for everyone, and especially for people with low vision or color blindness.
Does a high ΔE mean low WCAG contrast?
Not necessarily — they measure different things. Delta E 2000 measures perceptual difference between two colors regardless of role; WCAG contrast measures how readable one color is as text on the other as background. Two colors can be very different in hue (high ΔE) but very similar in luminance (low WCAG contrast) — for example, a saturated red and a saturated blue. They can also be similar in hue (low ΔE) but different enough in lightness (high WCAG contrast) — a mid-grey and a light grey.
Can I compare more than two colors?
Not with this tool — this is a pair-wise comparator. For side-by-side comparison of three or more colors, use the palette builder (coming soon) or the individual Pantone pages, which show each color alongside eight perceptually closest neighbors.
Are the two colors I compare sent anywhere?
No. Everything runs in your browser. The Pantone catalog is embedded in the page, and both color values are processed entirely client-side using JavaScript. No server request is made when you compare colors.