Hand Calculate Planned Contrast
Hand calculating planned contrast is crucial for ensuring web accessibility. It helps determine if there’s enough contrast between text and its background, making content readable for everyone, including those with visual impairments.
- Choose the background color.
- Choose the foreground (text) color.
- Enter the font size.
- Click ‘Calculate’.
The formula for calculating contrast is: (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 calculated as: (0.2126 * R) + (0.7152 * G) + (0.0722 * B), where R, G, and B are the sRGB values of the color.
| Font Size | Small Text | Large Text |
|---|---|---|
| 18px | 4.5:1 | 3:1 |
| 24px | 3:1 | 1.5:1 |
- Use tools like WebAIM’s Contrast Checker for quick checks.
- Consider color blindness when choosing colors.
- Test your designs with users to ensure they’re accessible.
What is the recommended contrast ratio for body text?
4.5:1 for small text (under 18pt) and 3:1 for large text (18pt and above).
WCAG Guidelines and WebAIM’s Contrast Checker are excellent resources for understanding and testing contrast.