#183F8F
Closest named color: Cobalt (#1E488F). oklch(39.2% 0.14 262.4), rgb(24, 63, 143).
Aa
White text reads best on this color (9.78:1).
About this color
#183F8F is a dark, vivid blue. In OKLCH its lightness is 39%, its chroma 0.140 and its hue 262°. Its hue sits on the cool side of the wheel. The nearest named color is Cobalt (#1E488F), ΔE 0.026 away. White text reads best on it, at 9.78:1.
| Hue family | Blues |
| Lightness | dark (39%) |
| Chroma | vivid (0.140) |
| Temperature | cool |
| Nearest name | Cobalt (#1E488F) |
| Black text | 2.14:1 |
| White text | 9.78:1 |
Values
| HEX | #183F8F |
| RGB | rgb(24, 63, 143) |
| HSL | hsl(220, 71%, 33%) |
| OKLCH | oklch(39.2% 0.14 262.4) |
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 #183F8F | 9.78:1 | AAA | Lc -96.4 | Preferred for body text |
| Black text on #183F8F | 2.14:1 | Fails | Lc 11.8 | Not readable |
| #183F8F text on white | 9.78:1 | AAA | Lc 92.2 | Preferred for body text |
| #183F8F text on black | 2.14:1 | Fails | Lc -10.3 | 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
#9FC1FF
oklch(80.9% 0.096 262.2)
-
Step 400
400
#6C9EFF
oklch(70.7% 0.152 262.5)
-
Step 500
500
#4381FF
oklch(63% 0.199 262.5)
-
Step 600
600
#1B63F9
oklch(55.6% 0.234 262.5)
-
Step 700
700
#0E51D9
oklch(49.2% 0.217 262.4)
-
Step 800
800
#0F43AF
oklch(42.6% 0.18 262.4)
-
Step 900
900 (this color)
#183F8F
oklch(39.2% 0.14 262.4)
-
Step 950
950
#0D2351
oklch(27% 0.089 262.7)
#183F8F 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) | #004992 | 0.027 |
| Deuteranopia (no green cones) | #003F8D | 0.013 |
| Tritanopia (no blue cones) | #005360 | 0.109 |
| Achromatopsia (no color) | #444444 | 0.140 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #183F8F
#183F8F
oklch(39.2% 0.14 262.4)
- #5B4000
#5B4000
oklch(39.1% 0.081 81.5)
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 #183F8F, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cobalt #1E488F ΔE 0.026
- Twilight Blue #0A437A ΔE 0.039
- Sapphire #2138AB ΔE 0.049
- Light Navy #155084 ΔE 0.054
- Blueberry #464196 ΔE 0.059
- Dark Slate Blue #483D8B ΔE 0.061
- Dusk Blue #26538D ΔE 0.061
- Deep Sea Blue #015482 ΔE 0.067
Use #183F8F 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.