Free tool · Design
Slide contrast checker: is your text readable on its background?
Pick a text color and a background color. You get the WCAG 2.2 contrast ratio, a pass or fail for each text size, a live slide in your colors and the nearest colors that pass.
- Free
- No account needed
- Runs in your browser
How to use the slide contrast checker
Enter the two colors
Pick the text color and the background color with the color pickers, or type hex codes such as #1a1530. The presets show common pairs, and the swap button flips text and background.
Read the ratio
The ratio counts up on a scale from 1 to 21 with marks at 3, 4.5 and 7. The line under it says for which text sizes the pair is safe.
Look at the live slide
The preview shows a title, body text and chart bars in your colors, so you see the pair the way the audience will.
Take the nearest passing color
Choose a goal, then use the card that changes the text or the card that changes the background. Both keep the hue and move only the lightness, and the smaller change is marked.
Build the deck in these colors
The button puts your pair into a brief that tells the AI to keep every page at level AA and to say which pairs it had to adjust.
Sources
How it works and what it rests on
Where a number is our own rule of thumb, we say so.
The tool measures the contrast ratio defined in the Web Content Accessibility Guidelines (WCAG) 2.2 of the W3C. It runs in your browser and compares exactly two flat colors. Thresholds as of October 2026.
The formula: each color channel of the sRGB color is converted to a linear value (a channel at or below 0.04045 is divided by 12.92, otherwise it is raised as ((c + 0.055) / 1.055) to the power 2.4). The relative luminance is L = 0.2126 R + 0.7152 G + 0.0722 B. The ratio is (L1 + 0.05) / (L2 + 0.05), where L1 belongs to the lighter color. It is 1 to 1 for identical colors and 21 to 1 for black on white. The older cut-off of 0.03928 gives the same result for every 8-bit color.
The thresholds come from three WCAG success criteria. 1.4.3 Contrast (Minimum), level AA, asks for 4.5 to 1 for text and 3 to 1 for large text. 1.4.6 Contrast (Enhanced), level AAA, asks for 7 to 1 and 4.5 to 1 for large text. 1.4.11 Non-text Contrast, level AA, asks for 3 to 1 for graphics that are needed to understand the content, such as chart bars, icons and the outlines of controls. WCAG defines large text as 18 point or larger, or 14 point or larger in bold.
Display: the tool cuts the ratio to two decimals instead of rounding it, so 4.4781 shows as 4.47 and fails 4.5, and a pair that misses by a hair never looks like a pass. This strict reading is our choice.
Nearest passing color: the search keeps the hue and saturation of the color in HSL and moves only the lightness in steps of 0.1 percent, first toward black and then toward white, until the goal is met. Each step is tested on the rounded 8-bit color, so the hex code shown really passes. Of the darker and the lighter result, the tool marks the one with the smaller distance in RGB. WCAG does not prescribe such a method, so this is our approach, and the result may not match your brand color. Use it as a starting point. For some pairs no color of the same hue reaches the goal on one side, and the tool then says so.
Reading the result: the tool measures the contrast of two solid colors and holds every text to the same threshold. For a gradient, check the spot with the lowest contrast; for a semi-transparent layer, enter the blended color. Contrast ratio measures lightness, not hue. A projector, a bright room and the distance to the screen weaken contrast in practice, so for a presentation in a bright room we suggest a margin above the minimum, for example 7 to 1 for body text. That is our advice, not a WCAG requirement.
Data: the colors stay in your browser. Only if you press the button under the tool, the two colors travel in the brief in the link to Slaide's sign-up page.
FAQ
Frequently asked questions
What contrast ratio does text on a slide need?
For WCAG 2.2 level AA, normal text needs at least 4.5 to 1 against its background, and large text needs 3 to 1. Level AAA raises these to 7 to 1 and 4.5 to 1. Black on white is 21 to 1, the maximum, and identical colors give 1 to 1.
What counts as large text in WCAG?
Text of 18 point or more, or 14 point or more in bold. On a slide, titles and big numbers usually qualify, while body text, captions, footnotes and chart labels usually do not. If a pair passes only the large-text level, use it for titles and keep it away from small text.
Do charts and icons need contrast too?
Yes. WCAG 2.2 success criterion 1.4.11 asks for at least 3 to 1 for graphics that are needed to understand the content, such as chart bars, lines, icons and control outlines. The checker shows this as its own line next to the text results.
How do I check contrast in PowerPoint?
Under Review, choose Check Accessibility. The checker flags hard-to-read text contrast, as of October 2026. It does not suggest a color pair, so use this tool while you choose the colors, then run the PowerPoint check on the finished deck.
Is white text on orange or coral readable?
Often not for small text. White on a bright coral such as #ff5b3a measures 3.08 to 1, which passes only for large text. A deeper #e62700 reaches 4.51 to 1 and passes for body text. Paste your own color to find the nearest shade that passes.
How does the tool find the nearest passing color?
It keeps the hue and saturation and moves only the lightness in steps of 0.1 percent, darker and lighter, until your goal is met, and it marks the result with the smaller change. This is our own method and WCAG does not prescribe one. Check that the new color still fits your brand.
Does it work for gradients and photos?
Not directly, because it compares two flat colors. For a gradient, test the text against the spot with the lowest contrast. For a photo, put a solid or semi-transparent panel behind the text and test the text against the blended color of that panel.
Are my colors sent anywhere?
No, the calculation runs in your browser. Only if you press the button under the tool, the two colors travel in the brief in the link to the editor's sign-up page. The brief is shown under What the editor receives, so you can read it first.
Keep reading
Charts and numbers
- GuideChoosing the right chart
Which chart fits which message: bars to compare, lines for trends, a waterfall for bridges. Includes when a pie works, when a table beats a chart, common traps.
- GlossaryDriver tree
A driver tree breaks a metric such as revenue or profit into the measurable drivers behind it, linked by simple math. See a worked example you can copy.
- GlossaryChartjunk
Chartjunk is decoration in a chart that does not help the reader understand the data, a term from Edward Tufte. Examples, the erase test and what research says.
- GlossaryWaterfall chart
A waterfall chart shows how a start value becomes an end value through a series of increases and decreases. Definition, how to read it and typical mistakes.
- GlossaryGantt chart
A Gantt chart shows a project's tasks as bars on a time axis, with milestones as markers. Definition, how to read it and how to simplify it for a slide.
- GlossaryTwo-by-two matrix
A two-by-two matrix sorts items into four quadrants using two criteria. Definition, well-known examples such as the Eisenhower matrix, and how to build one.
Put it into a finished deck
Describe your talk in a sentence, add your files and get an editable PowerPoint deck. The brief from this page is filled in for you.
Build this presentationFree plan, no card needed