#1E1B4B on white
Tailwind indigo-950 — roughly Deep Indigo — measured against white to WCAG 2.2 and APCA.
15.99:1
contrast ratio · APCA Lc 100
The quick brown fox
…and the same at 13 px
…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)
Where you can use it
#1E1B4B clears AAA on white, so it works for body copy at any size, including the 7:1 bar most teams only aim at for long-form reading. It also clears the 3:1 required of borders, icons and focus rings.
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.
| Vision | Foreground | Background | Ratio |
|---|---|---|---|
| Normal | #1E1B4B |
#FFFFFF |
15.99:1 |
| Protanopia red-blind, ~1% of men |
#1D1D43 |
#FFFFFF |
16.04:1 |
| Deuteranopia green-blind, ~6% of men |
#1D1D41 |
#FFFFFF |
16.10:1 |
| Tritanopia blue-blind, rare |
#1E3C3A |
#FFFFFF |
11.91:1 |
What the thresholds mean
- 4.5:1 — WCAG 2.2 success criterion 1.4.3, the minimum for body text.
- 3:1 — the minimum for large text (18.66 px bold or 24 px regular) and, under 1.4.11, for any non-text thing you have to perceive: input borders, icons, focus indicators.
- 7:1 — AAA, criterion 1.4.6.
- APCA Lc 100 — a perceptual model that accounts for polarity, so dark-on-light and light-on-dark are not treated as the same problem. It is the direction WCAG 3 is heading and it disagrees with the ratio often enough to be worth reading alongside it.
Related
One passing pair is not a system
ColorsMine checks every pairing a palette implies, in light and dark, and names the single change that moves the grade most.
Open ColorsMine