#183D8E
Closest named color: Cobalt (#1E488F). oklch(38.7% 0.141 263), rgb(24, 61, 142).
Aa
White text reads best on this color (10.01:1).
About this color
#183D8E is a dark, vivid blue. In OKLCH its lightness is 39%, its chroma 0.141 and its hue 263°. Its hue sits on the cool side of the wheel. The nearest named color is Cobalt (#1E488F), ΔE 0.032 away. White text reads best on it, at 10.01:1.
| Hue family | Blues |
| Lightness | dark (39%) |
| Chroma | vivid (0.141) |
| Temperature | cool |
| Nearest name | Cobalt (#1E488F) |
| Black text | 2.09:1 |
| White text | 10.01:1 |
Values
| HEX | #183D8E |
| RGB | rgb(24, 61, 142) |
| HSL | hsl(221, 71%, 33%) |
| OKLCH | oklch(38.7% 0.141 263) |
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 #183D8E | 10.01:1 | AAA | Lc -96.9 | Preferred for body text |
| Black text on #183D8E | 2.09:1 | Fails | Lc 11.2 | Not readable |
| #183D8E text on white | 10.01:1 | AAA | Lc 92.7 | Preferred for body text |
| #183D8E text on black | 2.09:1 | Fails | Lc -9.7 | 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 900.
-
Step 50
50
#F1F6FF
oklch(97.2% 0.013 262.4)
-
Step 100
100
#DFEAFF
oklch(93.5% 0.031 263.5)
-
Step 200
200
#C6DAFF
oklch(88.5% 0.056 262.8)
-
Step 300
300
#A0C1FF
oklch(80.9% 0.095 262.7)
-
Step 400
400
#6D9EFF
oklch(70.8% 0.152 262.8)
-
Step 500
500
#4681FF
oklch(63.1% 0.198 263.1)
-
Step 600
600
#1F62FA
oklch(55.6% 0.236 263)
-
Step 700
700
#1350DA
oklch(49.2% 0.219 263)
-
Step 800
800
#1243B0
oklch(42.8% 0.181 262.9)
-
Step 900
900 (this color)
#183D8E
oklch(38.7% 0.141 263)
-
Step 950
950
#0D2351
oklch(27% 0.089 262.7)
#183D8E 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) | #004891 | 0.029 |
| Deuteranopia (no green cones) | #003D8C | 0.014 |
| Tritanopia (no blue cones) | #00515F | 0.109 |
| Achromatopsia (no color) | #424242 | 0.141 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #183D8E
#183D8E
oklch(38.7% 0.141 263)
- #593F00
#593F00
oklch(38.6% 0.08 82.1)
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 #183D8E, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cobalt #1E488F ΔE 0.032
- Twilight Blue #0A437A ΔE 0.040
- Sapphire #2138AB ΔE 0.050
- Light Navy #155084 ΔE 0.058
- Blueberry #464196 ΔE 0.062
- Dark Slate Blue #483D8B ΔE 0.062
- Marine Blue #01386A ΔE 0.066
- Dusk Blue #26538D ΔE 0.066
Use #183D8E 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.