#183B5B
Closest named color: Prussian Blue (#1D3557). oklch(34.3% 0.069 248.7), rgb(24, 59, 91).
Aa
White text reads best on this color (11.56:1).
About this color
#183B5B is a dark, muted blue. In OKLCH its lightness is 34%, its chroma 0.069 and its hue 249°. Its hue sits on the cool side of the wheel. The nearest named color is Prussian Blue (#1D3557), ΔE 0.019 away. White text reads best on it, at 11.56:1.
| Hue family | Blues |
| Lightness | dark (34%) |
| Chroma | muted (0.069) |
| Temperature | cool |
| Nearest name | Prussian Blue (#1D3557) |
| Black text | 1.81:1 |
| White text | 11.56:1 |
Values
| HEX | #183B5B |
| RGB | rgb(24, 59, 91) |
| HSL | hsl(209, 58%, 23%) |
| OKLCH | oklch(34.3% 0.069 248.7) |
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 #183B5B | 11.56:1 | AAA | Lc -100.1 | Preferred for body text |
| Black text on #183B5B | 1.81:1 | Fails | Lc 7.5 | Not readable |
| #183B5B text on white | 11.56:1 | AAA | Lc 96.4 | Preferred for body text |
| #183B5B text on black | 1.81:1 | Fails | Lc 0.0 | 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 900.
-
Step 50
50
#F2F6FA
oklch(97.1% 0.007 247.9)
-
Step 100
100
#E2EBF4
oklch(93.6% 0.016 248)
-
Step 200
200
#CBDBEC
oklch(88.5% 0.029 249.8)
-
Step 300
300
#A7C4E1
oklch(80.8% 0.052 248.5)
-
Step 400
400
#77A5D3
oklch(70.7% 0.084 249.1)
-
Step 500
500
#528EC7
oklch(63.1% 0.107 248.7)
-
Step 600
600
#3577B4
oklch(55.6% 0.116 249.2)
-
Step 700
700
#27649B
oklch(49.1% 0.108 249)
-
Step 800
800
#22527D
oklch(42.7% 0.088 248.5)
-
Step 900
900 (this color)
#183B5B
oklch(34.3% 0.069 248.7)
-
Step 950
950
#14283B
oklch(27% 0.044 248.6)
#183B5B 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) | #2D3C5C | 0.025 |
| Deuteranopia (no green cones) | #23365A | 0.018 |
| Tritanopia (no blue cones) | #004346 | 0.054 |
| Achromatopsia (no color) | #393939 | 0.069 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #183B5B
#183B5B
oklch(34.3% 0.069 248.7)
- #503107
#503107
oklch(34.3% 0.07 68.4)
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 #183B5B, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Prussian Blue #1D3557 ΔE 0.019
- Dark Blue Grey #1F3B4D ΔE 0.025
- Midnight Green #073B4C ΔE 0.031
- Marine Blue #01386A ΔE 0.033
- Dark Grey Blue #29465B ΔE 0.043
- Charcoal #264653 ΔE 0.046
- Marine #042E60 ΔE 0.048
- Gunmetal #293241 ΔE 0.049
Use #183B5B 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.