#B5100B
Closest named color: Rufous (#AE2012). oklch(49.1% 0.194 29.1), rgb(181, 16, 11).
Aa
White text reads best on this color (6.89:1).
About this color
#B5100B is a medium-dark, vivid red. In OKLCH its lightness is 49%, its chroma 0.194 and its hue 29°. Its hue sits on the warm side of the wheel. The nearest named color is Rufous (#AE2012), ΔE 0.016 away. White text reads best on it, at 6.89:1.
| Hue family | Reds |
| Lightness | medium-dark (49%) |
| Chroma | vivid (0.194) |
| Temperature | warm |
| Nearest name | Rufous (#AE2012) |
| Black text | 3.04:1 |
| White text | 6.89:1 |
Values
| HEX | #B5100B |
| RGB | rgb(181, 16, 11) |
| HSL | hsl(2, 89%, 38%) |
| OKLCH | oklch(49.1% 0.194 29.1) |
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 #B5100B | 6.89:1 | AA | Lc -86.7 | Fine for body text |
| Black text on #B5100B | 3.04:1 | AA large text | Lc 22.4 | Dividers and decoration only |
| #B5100B text on white | 6.89:1 | AA | Lc 81.6 | Fine for body text |
| #B5100B text on black | 3.04:1 | AA large text | Lc -20.3 | 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
#FEF3F1
oklch(97.2% 0.012 29.9)
-
Step 100
100
#FCE4E0
oklch(93.7% 0.027 28.9)
-
Step 200
200
#FACDC6
oklch(88.5% 0.052 28.5)
-
Step 300
300
#F7AA9E
oklch(80.9% 0.093 29.1)
-
Step 400
400
#EF7868
oklch(70.6% 0.15 29.2)
-
Step 500
500
#E64D3E
oklch(63% 0.192 29.1)
-
Step 600
600
#D2241B
oklch(55.7% 0.209 29)
-
Step 700
700 (this color)
#B5100B
oklch(49.1% 0.194 29.1)
-
Step 800
800
#93150F
oklch(42.7% 0.161 29)
-
Step 900
900
#761C15
oklch(37.7% 0.125 28.9)
-
Step 950
950
#46130E
oklch(27.1% 0.079 28.9)
#B5100B 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) | #4D4405 | 0.213 |
| Deuteranopia (no green cones) | #746600 | 0.189 |
| Tritanopia (no blue cones) | #C80014 | 0.039 |
| Achromatopsia (no color) | #5A5A5A | 0.195 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #B5100B
#B5100B
oklch(49.1% 0.194 29.1)
- #006D7A
#006D7A
oklch(49% 0.084 209.1)
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 #B5100B, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Rufous #AE2012 ΔE 0.016
- Firebrick #B22222 ΔE 0.017
- Scarlet #BE0119 ΔE 0.021
- Rust Red #AA2704 ΔE 0.028
- Rusty Red #AF2F0D ΔE 0.031
- Brown #A52A2A ΔE 0.037
- Lipstick Red #C0022F ΔE 0.038
- Burnt Red #9F2305 ΔE 0.045
Use #B5100B 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.