#243D8C
Closest named color: Cobalt (#1E488F). oklch(39% 0.135 266.7), rgb(36, 61, 140).
Aa
White text reads best on this color (9.90:1).
About this color
#243D8C is a dark, moderately saturated blue. In OKLCH its lightness is 39%, its chroma 0.135 and its hue 267°. Its hue sits on the cool side of the wheel. The nearest named color is Cobalt (#1E488F), ΔE 0.029 away. White text reads best on it, at 9.90:1.
| Hue family | Blues |
| Lightness | dark (39%) |
| Chroma | moderately saturated (0.135) |
| Temperature | cool |
| Nearest name | Cobalt (#1E488F) |
| Black text | 2.12:1 |
| White text | 9.90:1 |
Values
| HEX | #243D8C |
| RGB | rgb(36, 61, 140) |
| HSL | hsl(226, 59%, 35%) |
| OKLCH | oklch(39% 0.135 266.7) |
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 #243D8C | 9.90:1 | AAA | Lc -96.7 | Preferred for body text |
| Black text on #243D8C | 2.12:1 | Fails | Lc 11.4 | Not readable |
| #243D8C text on white | 9.90:1 | AAA | Lc 92.5 | Preferred for body text |
| #243D8C text on black | 2.12:1 | Fails | Lc -9.9 | 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
#E1EAFE
oklch(93.6% 0.029 266.4)
-
Step 200
200
#C8D9FF
oklch(88.5% 0.056 266.2)
-
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
#3861F4
oklch(55.6% 0.225 266.7)
-
Step 700
700
#2C4FD5
oklch(49.2% 0.209 266.8)
-
Step 800
800
#2442AC
oklch(42.8% 0.173 266.6)
-
Step 900
900 (this color)
#243D8C
oklch(39% 0.135 266.7)
-
Step 950
950
#132250
oklch(26.9% 0.087 266.8)
#243D8C 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) | #00488F | 0.033 |
| Deuteranopia (no green cones) | #003E8A | 0.024 |
| Tritanopia (no blue cones) | #00505E | 0.107 |
| Achromatopsia (no color) | #434343 | 0.135 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #243D8C
#243D8C
oklch(39% 0.135 266.7)
- #574100
#574100
oklch(38.9% 0.079 86.8)
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 #243D8C, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cobalt #1E488F ΔE 0.029
- Twilight Blue #0A437A ΔE 0.041
- Dark Slate Blue #483D8B ΔE 0.051
- Blueberry #464196 ΔE 0.052
- Sapphire #2138AB ΔE 0.052
- Light Navy #155084 ΔE 0.057
- Dusk Blue #26538D ΔE 0.062
- Marine Blue #01386A ΔE 0.067
Use #243D8C 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.