Mr Calcu | Make your content readable for everyone—check your color contrast in seconds and meet WCAG standards effortlessly.

Quickly evaluate and improve your color contrast to boost accessibility and ensure WCAG compliance—empower every user with clear, readable content.

Color Contrast Checker Description

Understanding Color Contrast

Color contrast is the difference in luminance between two adjacent colors—typically text and background. Ensuring strong contrast improves readability and supports inclusive design.

Why It Matters

• Improves readability for users with low vision or color blindness
• Ensures compliance with WCAG 2.1 standards
• Enhances UX in both light and dark mode interfaces

WCAG Requirements

• Normal text: Minimum 4.5:1 contrast ratio
• Large text (≥ 18pt or 14pt bold): Minimum 3:1 contrast ratio
• AAA compliance: 7:1 contrast ratio for normal text

How Contrast Ratio is Calculated

The contrast ratio is defined by WCAG using relative luminance:

Contrast Ratio = (L1 + 0.05) / (L2 + 0.05)

• L1: Luminance of the lighter color
• L2: Luminance of the darker color

Calculating Relative Luminance

For each RGB component (R, G, B):
  c' = c / 255
  If c' ≤ 0.03928:
    c'' = c' / 12.92
  Else:
    c'' = ((c' + 0.055) / 1.055)^2.4

Luminance = 0.2126 * R'' + 0.7152 * G'' + 0.0722 * B''

Common Edge Cases

• Near-identical colors: e.g., #F1F1F1 on #FFFFFF usually fails
• Different hues, same brightness: Can yield low contrast
• Opacity and overlays: Transparent layers distort real contrast
• Grayscale pairs: Light grays often don’t meet the 4.5:1 requirement
• Dark mode: Requires equal scrutiny for color pairings

Mini Case Studies

Healthcare App Redesign

• Before: #B0B0B0 text on #FFFFFF → 1.65:1 (Fail)
• After: #333333 text → 12.6:1 (AAA Pass)

Transit Website Hover State

• Before: #99BBEE on #FFFFFF → 2.1:1 (Fail)
• After: #2255AA → 5.8:1 (AA Pass)

Take action: Run your colors through the checker now and ensure every visitor can read your content clearly and confidently!