How this tool works
Contrast ratio uses relative luminance: (lighter + 0.05) / (darker + 0.05). Aim for at least 4.5:1 for normal body text.
Color Contrast Checker
Check contrast ratio between two hex colors using the WCAG relative luminance formula.
What it checks
The calculator compares foreground and background color contrast using relative luminance.
Example
Use it before publishing text over a colored button, banner or image background.
Common mistake
A color pair that looks stylish may still be hard to read for users with low vision or in bright light.
What to do with the answer
Check contrast ratio between two hex colors using the WCAG relative luminance formula. The useful part is not just the first answer; it is checking whether the answer still makes sense when the uncertain number changes.
Quick check
- Read the result label first so you know whether it is monthly, yearly, daily, a percentage, a date or a total.
- Change the input you are least sure about and compare the second answer with the first.
- Use a related guide or worksheet when the result affects a bill, budget, health target, study plan or purchase.
A better way to use this page
Run one realistic example, then run one cautious version. For a cost page that might mean a higher price or longer time. For a date page it might mean a different deadline. For a health, study or work page it might mean a more conservative target.
If both answers point to the same next step, the result is easier to trust as a rough planning number. If they are very different, the input you changed is the one to check before you rely on the answer.
Use it with real numbers
Color Contrast Checker is most useful when you open it with one actual thing in mind: a quote, bill, grade target, label, deadline, trade entry, measurement or plan you are trying to check. Sample numbers are fine for learning the page, but the result becomes more useful when it is tied to a real choice.
After the first answer, change one important input and calculate again. If the answer hardly moves, you have a steadier estimate. If it jumps, that input deserves attention before you compare options, save the result or share the link.
Use the links around the page to move from the number to the next action. A worksheet is better when you need notes or side-by-side options. A guide is better when the calculation needs context, definitions or common mistakes.