ColorsMine

#06B6D4 on white

Tailwind cyan-500 — roughly Cyan — measured against white to WCAG 2.2 and APCA.

2.43:1

contrast ratio · APCA Lc 45

The quick brown fox
…and the same at 13 px
✕ Body text (AA, 4.5:1) ✕ Body text (AAA, 7:1) ✕ Large text (AA, 3:1) ✕ Borders and icons (1.4.11, 3:1)

The nearest colour that passes

Keeping the hue and moving only the lightness, #00677E is the closest shade to #06B6D4 that clears 4.5:1 on white — at 6.48:1.

#06B6D4
2.43:1 — fails
#00677E
6.48:1 — passes

Under colour blindness

Contrast is a lightness relationship, so a ratio survives colour blindness — but the pair can still lose the distinction it was carrying. This is the same two colours as seen with each dichromacy.

VisionForegroundBackgroundRatio
Normal #06B6D4 #FFFFFF 2.43:1
Protanopia
red-blind, ~1% of men
#7D7ECD #FFFFFF 3.66:1
Deuteranopia
green-blind, ~6% of men
#7569CC #FFFFFF 4.52:1
Tritanopia
blue-blind, rare
#2CC8C6 #FFFFFF 2.06:1

What the thresholds mean

Related

Same colour on black The full cyan scale

Fixing one pair is not the job

ColorsMine checks every pairing a palette implies, in light and dark, and names the single change that moves the grade most.

Open ColorsMine