#900521
Closest named color: Dark Red (#8B0000). oklch(41.5% 0.164 20.9), rgb(144, 5, 33).
Aa
White text reads best on this color (9.41:1).
About this color
#900521 is a dark, vivid red. In OKLCH its lightness is 42%, its chroma 0.164 and its hue 21°. Its hue sits on the warm side of the wheel. The nearest named color is Dark Red (#8B0000), ΔE 0.028 away. White text reads best on it, at 9.41:1.
| Hue family | Reds |
| Lightness | dark (42%) |
| Chroma | vivid (0.164) |
| Temperature | warm |
| Nearest name | Dark Red (#8B0000) |
| Black text | 2.22:1 |
| White text | 9.41:1 |
Values
| HEX | #900521 |
| RGB | rgb(144, 5, 33) |
| HSL | hsl(348, 93%, 29%) |
| OKLCH | oklch(41.5% 0.164 20.9) |
Contrast
WCAG 2 contrast ratios are the conformance target: AA needs 4.5:1 for body text and 3:1 for large text, AAA needs 7:1. APCA Lc values are supplementary guidance from the WCAG 3 drafts.
| Pair | WCAG 2 | Result | APCA | APCA guidance |
|---|---|---|---|---|
| White text on #900521 | 9.41:1 | AAA | Lc -94.1 | Preferred for body text |
| Black text on #900521 | 2.22:1 | Fails | Lc 14.4 | Not readable |
| #900521 text on white | 9.41:1 | AAA | Lc 89.6 | Fine for body text |
| #900521 text on black | 2.22:1 | Fails | Lc -12.7 | Not readable |
Tints and shades
A 50–950 scale built in OKLCH: the hue is held, lightness follows a Tailwind v4-like curve, and every step is kept inside the sRGB gamut. This color sits at step 800.
-
Step 50
50
#FEF2F2
oklch(97.1% 0.013 17.4)
-
Step 100
100
#FCE3E2
oklch(93.6% 0.028 20.4)
-
Step 200
200
#FBCCCA
oklch(88.5% 0.054 21.1)
-
Step 300
300
#F9A8A6
oklch(81% 0.096 21)
-
Step 400
400
#F17576
oklch(70.8% 0.153 21.2)
-
Step 500
500
#E84853
oklch(63.1% 0.196 21.1)
-
Step 600
600
#D31938
oklch(55.6% 0.213 20.9)
-
Step 700
700
#B6002B
oklch(49.1% 0.197 20.8)
-
Step 800
800 (this color)
#900521
oklch(41.5% 0.164 20.9)
-
Step 900
900
#771922
oklch(37.7% 0.128 21)
-
Step 950
950
#461114
oklch(27% 0.081 21.3)
#900521 with color blindness
Simulated with the Machado et al. (2009) model. ΔE is how far the color moves: below about 0.02 you would not notice a change.
| Vision | Seen as | Shift (ΔE) |
|---|---|---|
| Protanopia (no red cones) | #393421 | 0.182 |
| Deuteranopia (no green cones) | #59501C | 0.166 |
| Tritanopia (no blue cones) | #9F0014 | 0.035 |
| Achromatopsia (no color) | #464646 | 0.165 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #900521
#900521
oklch(41.5% 0.164 20.9)
- #00575B
#00575B
oklch(41.5% 0.071 200.2)
Analogous
Neighbouring hues, 30° either side.
Split complementary
The two hues beside the complement (150° and 210°).
Triadic
Three hues spaced 120° apart.
Palettes with this color
Curated palettes that contain a color within ΔE 0.04 (OKLab) of #900521, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Dark Red #8B0000 ΔE 0.028
- Blood Red #980002 ΔE 0.029
- Red Wine #8C0034 ΔE 0.030
- Brick Red #8F1402 ΔE 0.030
- Carmine #9D0216 ΔE 0.030
- Deep Red #9A0200 ΔE 0.033
- Auburn #9B2226 ΔE 0.041
- Cranberry #9E003A ΔE 0.044
Use #900521 in your product
Turn it into light and dark UI roles checked for contrast, then export to Tailwind v4, shadcn/ui, CSS or design tokens.