About Pandaxq

Pandaxq is an independent set of tools for the two decisions that quietly determine whether an interface is readable: colour contrast and typographic scale. No account, no upload, no paywall.

Why it exists

Most contrast tooling is either buried inside a developer console — great if you already know what you are looking for — or locked behind a sign-up wall that makes a five-second check into a commitment. Pandaxq is the opposite: open the page, paste two hex values, get an answer you can send to a colleague as a link.

Everything runs client-side. The colours and numbers you enter are processed in your browser and are never transmitted to a server.

Method

Contrast ratios

We implement the relative luminance method defined in the W3C Web Content Accessibility Guidelines:

1. Each sRGB channel is normalised to 0–1 and linearised: values at or below 0.04045 are divided by 12.92; above that, the value is raised through the sRGB transfer function.
2. Relative luminance is the weighted sum 0.2126R + 0.7152G + 0.0722B.
3. The ratio between two colours is (Llighter + 0.05) / (Ldarker + 0.05).

Thresholds applied: 4.5:1 for normal text at AA, 3:1 for large text at AA, 7:1 and 4.5:1 for the equivalent AAA levels, and 3:1 for interface components and meaningful graphics. "Large text" follows the guideline definition — 18pt / 24px or larger, or 14pt / 18.66px or larger when bold.

Palette generation

Palettes are produced by rotating hue in HSL space from a base colour, using the standard harmony offsets: analogous at ±30°, complementary at 180°, triadic at 120° and 240°, split complementary at 150° and 210°, tetradic at 90° intervals, and monochromatic variation in lightness only. These are conventions, not rules — the generator gives you a starting point, and the contrast readout tells you what each colour can actually be used for.

Type scales

Scales use the modular formula size = base × ratiostep. Ratios are the conventional set inherited from musical intervals. Values are reported to one decimal place and deliberately not rounded to whole pixels, because rounding breaks the ratio you just chose.

Editorial policy

• Sources are primary where possible. Threshold figures are taken from the W3C recommendation rather than from other blogs that quote it.
• Every guide states its limits. Where a rule has exceptions, an edge case, or genuine disagreement in the field, we say so instead of presenting a clean answer that does not exist.
• No sponsored placements. No tool on this site takes payment to recommend a product, and no result is influenced by an advertiser.
• Corrections are visible. If a figure is wrong, we fix it and note the change. Reports are welcome — see below.
• Advertising does not touch results. Adverts appear in clearly marked slots and never inside the calculator output.

Limitations

Pandaxq checks numbers. It does not certify compliance, and it cannot see your page. Real accessibility review involves assistive technology, keyboard behaviour, content structure and user testing — none of which a contrast ratio can substitute for.

Contact

Corrections, bug reports and suggestions are genuinely welcome — especially cases where a calculation disagrees with another tool you trust.

• General & corrections: pandaxq1016@gmail.com
• Report a calculation error: include the two hex values, the ratio you expected, and the tool you compared against.

We aim to reply within a few working days. We cannot answer questions about your specific tax, legal or compliance situation.

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Pandaxq is an independent project and is not affiliated with the W3C or any standards body.