1. What is Contrast Ratio?

The contrast ratio is a numerical value that represents the difference in luminance between two colors. It's a crucial factor in web accessibility, determining how easily text can be read against its background.

2. How Does the Calculator Work?

The calculator uses the WCAG contrast ratio formula:

Where:

• \( L_1 \) — Relative luminance of the lighter color (0-1)
• \( L_2 \) — Relative luminance of the darker color (0-1)
• 0.05 — Offset to account for ambient light

Explanation: The equation compares the relative brightness of two colors, with higher values indicating greater contrast.

3. Importance of Contrast Ratio

Details: WCAG 2.1 requires a minimum contrast ratio of 4.5:1 for normal text and 3:1 for large text. For AA compliance, aim for at least 4.5:1; for AAA, 7:1.

4. Using the Calculator

Tips: Enter luminance values between 0 (black) and 1 (white). The calculator automatically ensures L1 is the lighter color. Values are typically calculated from RGB using luminance formulas.

5. Frequently Asked Questions (FAQ)

Q1: What's considered a good contrast ratio?
A: For web accessibility, 4.5:1 is the minimum for normal text, 7:1 is preferred for better readability.

Q2: How do I get luminance values from RGB?
A: Convert RGB to relative luminance using the formula: L = 0.2126*R + 0.7152*G + 0.0722*B (for sRGB colorspace).

Q3: Why is contrast ratio important?
A: It ensures content is accessible to people with visual impairments and readable in various lighting conditions.

Q4: Does this work for all color combinations?
A: Yes, but be aware that color perception can vary based on hue, not just luminance.

Q5: What's the maximum possible contrast ratio?
A: 21:1 (pure black on pure white or vice versa).