APCA Contrast Calculator
Next-generation perceptual contrast analysis for WCAG 3.0. Accounts for font size, weight, and human perception.
Contrast Ratio
12.6:1
AA Normal (≥4.5:1)
AA Large (≥3:1)
AAA Normal (≥7:1)
AAA Large (≥4.5:1)
Live Preview
The quick brown fox jumps over the lazy dog.
This is a large heading
Small secondary text — often used for captions
Features
- ✓ Perceptual contrast values (Lc)
- ✓ Font size & weight-aware calculation
- ✓ Side-by-side with WCAG 2.x results
- ✓ 100% free — processed in your browser
FAQ
What is APCA?
APCA (Advanced Perceptual Contrast Algorithm) is a next-generation contrast calculation method developed for WCAG 3.0. Unlike the WCAG 2.x formula (which only considers luminance), APCA accounts for font size, font weight, and human visual perception.
How is APCA different from WCAG 2.x?
WCAG 2.x is a simple ratio (e.g., 4.5:1). APCA produces an Lc (lightness contrast) value that varies based on text size and weight — thin small text needs much higher contrast than bold large text.
Is APCA replacing WCAG 2.x?
APCA is the candidate for WCAG 3.0, still under development. WCAG 2.x remains the current legal standard. We support both so you can prepare for the future.