#243C87
Closest named color: Cobalt (#1E488F). oklch(38.4% 0.129 266.8), rgb(36, 60, 135).
Aa
White text reads best on this color (10.13:1).
About this color
#243C87 is a dark, moderately saturated blue. In OKLCH its lightness is 38%, its chroma 0.129 and its hue 267°. Its hue sits on the cool side of the wheel. The nearest named color is Cobalt (#1E488F), ΔE 0.034 away. White text reads best on it, at 10.13:1.
| Hue family | Blues |
| Lightness | dark (38%) |
| Chroma | moderately saturated (0.129) |
| Temperature | cool |
| Nearest name | Cobalt (#1E488F) |
| Black text | 2.07:1 |
| White text | 10.13:1 |
Values
| HEX | #243C87 |
| RGB | rgb(36, 60, 135) |
| HSL | hsl(225, 58%, 34%) |
| OKLCH | oklch(38.4% 0.129 266.8) |
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 #243C87 | 10.13:1 | AAA | Lc -97.3 | Preferred for body text |
| Black text on #243C87 | 2.07:1 | Fails | Lc 10.8 | Not readable |
| #243C87 text on white | 10.13:1 | AAA | Lc 93.1 | Preferred for body text |
| #243C87 text on black | 2.07:1 | Fails | Lc -9.3 | 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
#F1F5FF
oklch(97% 0.014 268.5)
-
Step 100
100
#E1EAFD
oklch(93.6% 0.028 265.4)
-
Step 200
200
#C9D9FE
oklch(88.5% 0.054 266.8)
-
Step 300
300
#A5BFFF
oklch(80.9% 0.095 267.2)
-
Step 400
400
#759BFF
oklch(70.6% 0.153 266.8)
-
Step 500
500
#537EFF
oklch(63.1% 0.197 266.8)
-
Step 600
600
#3B63EF
oklch(55.7% 0.215 266.9)
-
Step 700
700
#2E51D0
oklch(49.2% 0.2 266.8)
-
Step 800
800
#2643A8
oklch(42.7% 0.166 266.8)
-
Step 900
900 (this color)
#243C87
oklch(38.4% 0.129 266.8)
-
Step 950
950
#14234E
oklch(27.1% 0.082 266.5)
#243C87 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) | #02468A | 0.031 |
| Deuteranopia (no green cones) | #003D86 | 0.024 |
| Tritanopia (no blue cones) | #004E5B | 0.104 |
| Achromatopsia (no color) | #414141 | 0.129 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #243C87
#243C87
oklch(38.4% 0.129 266.8)
- #554000
#554000
oklch(38.4% 0.078 87.5)
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 #243C87, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cobalt #1E488F ΔE 0.034
- Twilight Blue #0A437A ΔE 0.036
- Dark Slate Blue #483D8B ΔE 0.053
- Blueberry #464196 ΔE 0.057
- Light Navy #155084 ΔE 0.057
- Marine Blue #01386A ΔE 0.059
- Sapphire #2138AB ΔE 0.060
- Dusk Blue #26538D ΔE 0.065
Use #243C87 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.