#243B78
Closest named color: Twilight Blue (#0A437A). oklch(37% 0.108 265.8), rgb(36, 59, 120).
Aa
White text reads best on this color (10.65:1).
About this color
#243B78 is a dark, moderately saturated blue. In OKLCH its lightness is 37%, its chroma 0.108 and its hue 266°. Its hue sits on the cool side of the wheel. The nearest named color is Twilight Blue (#0A437A), ΔE 0.027 away. White text reads best on it, at 10.65:1.
| Hue family | Blues |
| Lightness | dark (37%) |
| Chroma | moderately saturated (0.108) |
| Temperature | cool |
| Nearest name | Twilight Blue (#0A437A) |
| Black text | 1.97:1 |
| White text | 10.65:1 |
Values
| HEX | #243B78 |
| RGB | rgb(36, 59, 120) |
| HSL | hsl(224, 54%, 31%) |
| OKLCH | oklch(37% 0.108 265.8) |
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 #243B78 | 10.65:1 | AAA | Lc -98.4 | Preferred for body text |
| Black text on #243B78 | 1.97:1 | Fails | Lc 9.5 | Not readable |
| #243B78 text on white | 10.65:1 | AAA | Lc 94.4 | Preferred for body text |
| #243B78 text on black | 1.97:1 | Fails | Lc -8.2 | 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
#F2F5FD
oklch(97% 0.011 269.6)
-
Step 100
100
#E2EAFA
oklch(93.6% 0.023 264.5)
-
Step 200
200
#CBD9F8
oklch(88.5% 0.045 266.2)
-
Step 300
300
#A8C0F6
oklch(80.9% 0.081 266)
-
Step 400
400
#7A9EF2
oklch(70.8% 0.13 265.6)
-
Step 500
500
#5983ED
oklch(63.2% 0.166 265.6)
-
Step 600
600
#4069DB
oklch(55.5% 0.181 265.8)
-
Step 700
700
#3357BE
oklch(49.1% 0.167 265.9)
-
Step 800
800
#2A489A
oklch(42.8% 0.139 265.7)
-
Step 900
900 (this color)
#243B78
oklch(37% 0.108 265.8)
-
Step 950
950
#162448
oklch(26.9% 0.07 265.9)
#243B78 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) | #1A427A | 0.021 |
| Deuteranopia (no green cones) | #043B77 | 0.024 |
| Tritanopia (no blue cones) | #004953 | 0.089 |
| Achromatopsia (no color) | #3E3E3E | 0.108 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #243B78
#243B78
oklch(37% 0.108 265.8)
- #513C00
#513C00
oklch(36.9% 0.076 86.3)
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 #243B78, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Twilight Blue #0A437A ΔE 0.027
- Marine Blue #01386A ΔE 0.039
- Cobalt #1E488F ΔE 0.050
- Prussian Blue #1D3557 ΔE 0.059
- Light Navy #155084 ΔE 0.061
- Dark Slate Blue #483D8B ΔE 0.063
- Marine #042E60 ΔE 0.066
- Dark Grey Blue #29465B ΔE 0.067
Use #243B78 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.