#B10A21
Closest named color: Firebrick (#B22222). oklch(48.3% 0.191 24.1), rgb(177, 10, 33).
Aa
White text reads best on this color (7.15:1).
About this color
#B10A21 is a medium-dark, vivid red. In OKLCH its lightness is 48%, its chroma 0.191 and its hue 24°. Its hue sits on the warm side of the wheel. The nearest named color is Firebrick (#B22222), ΔE 0.020 away. White text reads best on it, at 7.15:1.
| Hue family | Reds |
| Lightness | medium-dark (48%) |
| Chroma | vivid (0.191) |
| Temperature | warm |
| Nearest name | Firebrick (#B22222) |
| Black text | 2.93:1 |
| White text | 7.15:1 |
Values
| HEX | #B10A21 |
| RGB | rgb(177, 10, 33) |
| HSL | hsl(352, 89%, 37%) |
| OKLCH | oklch(48.3% 0.191 24.1) |
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 #B10A21 | 7.15:1 | AAA | Lc -87.6 | Fine for body text |
| Black text on #B10A21 | 2.93:1 | Fails | Lc 21.5 | Dividers and decoration only |
| #B10A21 text on white | 7.15:1 | AAA | Lc 82.5 | Fine for body text |
| #B10A21 text on black | 2.93:1 | Fails | Lc -19.4 | 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
#FEF2F1
oklch(97% 0.013 23.2)
-
Step 100
100
#FBE3E1
oklch(93.5% 0.027 23.4)
-
Step 200
200
#FACDC9
oklch(88.6% 0.051 24.1)
-
Step 300
300
#F7A9A4
oklch(80.9% 0.093 23.4)
-
Step 400
400
#EE7872
oklch(70.7% 0.147 24.5)
-
Step 500
500
#E54D4E
oklch(63.1% 0.188 23.9)
-
Step 600
600
#D12431
oklch(55.7% 0.205 24.1)
-
Step 700
700 (this color)
#B10A21
oklch(48.3% 0.191 24.1)
-
Step 800
800
#92151F
oklch(42.6% 0.158 24)
-
Step 900
900
#751C1F
oklch(37.6% 0.123 23.7)
-
Step 950
950
#451313
oklch(27% 0.077 23.8)
#B10A21 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) | #494220 | 0.211 |
| Deuteranopia (no green cones) | #706319 | 0.189 |
| Tritanopia (no blue cones) | #C40017 | 0.040 |
| Achromatopsia (no color) | #585858 | 0.192 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #B10A21
#B10A21
oklch(48.3% 0.191 24.1)
- #006B74
#006B74
oklch(48.2% 0.082 205)
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 #B10A21, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Firebrick #B22222 ΔE 0.020
- Rufous #AE2012 ΔE 0.023
- Scarlet #BE0119 ΔE 0.027
- Rouge #AB1239 ΔE 0.029
- Brown #A52A2A ΔE 0.031
- Lipstick Red #C0022F ΔE 0.034
- Rust Red #AA2704 ΔE 0.036
- Rose Red #BE013C ΔE 0.041
Use #B10A21 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.