Deck Contrast Auditor

Add the deck palette

Use 2–10 colours in the order they commonly appear together on slides.

Why contrast is a slide design problem, not an accessibility footnote

A palette that reads perfectly on your laptop can disappear on a projector. The failure is systematic, and it has three causes worth knowing before you pick presentation slide colours.

Projectors wash out. A meeting-room projector in a lit room loses a large share of the contrast your monitor shows you. Mid-tone accents that look confident on screen turn into grey mush on the wall — which is why the check below targets ratios rather than trusting your eye.

Adjacent colours matter as much as the background. Most palette checkers only compare each colour against the slide background. On a chart, two series sit next to each other, and if those two fail against each other, the legend becomes the only way to read the data. That is why this tool checks every adjacent pair as well.

Roughly one in twelve men has a colour vision deficiency. A red-and-green comparison that is obvious to you is a single colour to part of your audience. Contrast is what keeps the distinction legible when hue does not.

The practical rules for slide design: non-text marks such as bars, lines, and icons want at least 3:1 against the background; body text wants 4.5:1; and any two colours that touch or sit adjacent in a chart want 3:1 against each other. Beautiful slides usually fail on the second and third, not the first.

Common questions

Does this change my deck? No. Nothing is uploaded, nothing is stored, and the tool returns arithmetic — background ratios, adjacent-pair ratios, and a repaired alternative colour for anything that fails. What you do with the result is up to you.

Why do the numbers never change between runs? Because there is no AI model in the path. The same palette always returns the same ratios, which is what makes the check usable as a gate rather than a suggestion.

What if my brand colours fail? Brand palettes are chosen for logos and websites, not for text on a projected slide, so failures are common and not usually a reason to abandon the brand. Use the suggested alternative for the on-slide variant, keep the brand colour for large fills and logos, and reserve the failing colour for places where nothing has to be read out of it.

Do I need to check every slide? Check the palette, not the slides. If the background, body text colour, and the accents all pass here, the deck inherits that everywhere the theme is applied consistently.