#B31D09
Closest named color: Rufous (#AE2012). oklch(49.4% 0.186 30.9), rgb(179, 29, 9).
Aa
White text reads best on this color (6.78:1).
About this color
#B31D09 is a medium-dark, vivid red. In OKLCH its lightness is 49%, its chroma 0.186 and its hue 31°. Its hue sits on the warm side of the wheel. The nearest named color is Rufous (#AE2012), ΔE 0.010 away. White text reads best on it, at 6.78:1.
| Hue family | Reds |
| Lightness | medium-dark (49%) |
| Chroma | vivid (0.186) |
| Temperature | warm |
| Nearest name | Rufous (#AE2012) |
| Black text | 3.09:1 |
| White text | 6.78:1 |
Values
| HEX | #B31D09 |
| RGB | rgb(179, 29, 9) |
| HSL | hsl(7, 90%, 37%) |
| OKLCH | oklch(49.4% 0.186 30.9) |
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 #B31D09 | 6.78:1 | AA | Lc -86.6 | Fine for body text |
| Black text on #B31D09 | 3.09:1 | AA large text | Lc 22.5 | Dividers and decoration only |
| #B31D09 text on white | 6.78:1 | AA | Lc 81.5 | Fine for body text |
| #B31D09 text on black | 3.09:1 | AA large text | Lc -20.4 | Dividers and decoration only |
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 700.
-
Step 50
50
#FDF3F1
oklch(97.1% 0.011 31.1)
-
Step 100
100
#FBE4DF
oklch(93.6% 0.026 32.2)
-
Step 200
200
#F9CEC5
oklch(88.6% 0.05 31.8)
-
Step 300
300
#F5AB9D
oklch(80.8% 0.09 31)
-
Step 400
400
#EC7B68
oklch(70.7% 0.143 30.9)
-
Step 500
500
#E3523D
oklch(63.1% 0.184 31)
-
Step 600
600
#CE2D18
oklch(55.6% 0.2 31)
-
Step 700
700 (this color)
#B31D09
oklch(49.4% 0.186 30.9)
-
Step 800
800
#911C0D
oklch(42.8% 0.154 30.9)
-
Step 900
900
#742014
oklch(37.7% 0.12 31.2)
-
Step 950
950
#44140D
oklch(26.9% 0.076 30.9)
#B31D09 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) | #504602 | 0.201 |
| Deuteranopia (no green cones) | #746700 | 0.180 |
| Tritanopia (no blue cones) | #C6001C | 0.041 |
| Achromatopsia (no color) | #5B5B5B | 0.188 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #B31D09
#B31D09
oklch(49.4% 0.186 30.9)
- #006E7D
#006E7D
oklch(49.4% 0.086 211.1)
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 #B31D09, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Rufous #AE2012 ΔE 0.010
- Firebrick #B22222 ΔE 0.015
- Rust Red #AA2704 ΔE 0.020
- Rusty Red #AF2F0D ΔE 0.021
- Scarlet #BE0119 ΔE 0.027
- Brown #A52A2A ΔE 0.034
- Burnt Red #9F2305 ΔE 0.041
- Brick #A03623 ΔE 0.043
Use #B31D09 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.