1. What is Contrast Ratio?

The contrast ratio is a measure of the difference in luminance between two colors, typically used in display technology and web accessibility. It ranges from 0 (no contrast) to 1 (maximum contrast).

2. How Does the Calculator Work?

The calculator uses the contrast ratio formula:

Where:

• \( L_{\text{max}} \) — Maximum luminance (cd/m²)
• \( L_{\text{min}} \) — Minimum luminance (cd/m²)

Explanation: The formula calculates the relative difference between the brightest and darkest values, normalized by their sum.

3. Importance of Contrast Ratio

Details: Contrast ratio is crucial for readability in displays, web design accessibility (WCAG guidelines recommend minimum 4.5:1 for normal text), and visual perception studies.

4. Using the Calculator

Tips: Enter both luminance values in candelas per square meter (cd/m²). Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is a good contrast ratio for displays?
A: For most applications, a contrast ratio of at least 1000:1 is considered good, while professional displays may achieve 3000:1 or higher.

Q2: How does this relate to WCAG accessibility standards?
A: WCAG converts this ratio to a simpler form (e.g., 4.5:1) by dividing Lmax by Lmin. Our calculation shows the normalized difference.

Q3: What are typical luminance values?
A: Computer monitors typically range from 50-300 cd/m², while HDR displays can reach 1000+ cd/m².

Q4: Can this be used for color contrast?
A: Yes, but you must first convert colors to their relative luminance values before applying this formula.

Q5: Why is contrast ratio dimensionless?
A: Because it's a ratio of two quantities with the same units, the units cancel out.