#243F79
Closest named color: Twilight Blue (#0A437A). oklch(37.9% 0.104 263.5), rgb(36, 63, 121).
Aa
White text reads best on this color (10.18:1).
About this color
#243F79 is a dark, moderately saturated blue. In OKLCH its lightness is 38%, its chroma 0.104 and its hue 263°. Its hue sits on the cool side of the wheel. The nearest named color is Twilight Blue (#0A437A), ΔE 0.020 away. White text reads best on it, at 10.18:1.
| Hue family | Blues |
| Lightness | dark (38%) |
| Chroma | moderately saturated (0.104) |
| Temperature | cool |
| Nearest name | Twilight Blue (#0A437A) |
| Black text | 2.06:1 |
| White text | 10.18:1 |
Values
| HEX | #243F79 |
| RGB | rgb(36, 63, 121) |
| HSL | hsl(221, 54%, 31%) |
| OKLCH | oklch(37.9% 0.104 263.5) |
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 #243F79 | 10.18:1 | AAA | Lc -97.5 | Preferred for body text |
| Black text on #243F79 | 2.06:1 | Fails | Lc 10.6 | Not readable |
| #243F79 text on white | 10.18:1 | AAA | Lc 93.4 | Preferred for body text |
| #243F79 text on black | 2.06:1 | Fails | Lc -9.1 | 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
#F2F6FD
oklch(97.2% 0.01 261.8)
-
Step 100
100
#E2EAFA
oklch(93.6% 0.023 264.5)
-
Step 200
200
#CADAF7
oklch(88.5% 0.044 262.4)
-
Step 300
300
#A7C1F4
oklch(80.9% 0.078 263.6)
-
Step 400
400
#789FEF
oklch(70.8% 0.125 263.7)
-
Step 500
500
#5585E9
oklch(63.1% 0.159 263.3)
-
Step 600
600
#3B6CD7
oklch(55.6% 0.173 263.4)
-
Step 700
700
#2E59BB
oklch(49.1% 0.162 263.7)
-
Step 800
800
#264A97
oklch(42.8% 0.133 263.1)
-
Step 900
900 (this color)
#243F79
oklch(37.9% 0.104 263.5)
-
Step 950
950
#152546
oklch(27% 0.065 263.2)
#243F79 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) | #22457B | 0.017 |
| Deuteranopia (no green cones) | #113E78 | 0.018 |
| Tritanopia (no blue cones) | #004C56 | 0.084 |
| Achromatopsia (no color) | #414141 | 0.104 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #243F79
#243F79
oklch(37.9% 0.104 263.5)
- #563E00
#563E00
oklch(38% 0.078 83.8)
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 #243F79, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Twilight Blue #0A437A ΔE 0.020
- Cobalt #1E488F ΔE 0.042
- Marine Blue #01386A ΔE 0.045
- Light Navy #155084 ΔE 0.050
- Dark Slate Blue #483D8B ΔE 0.060
- Dark Grey Blue #29465B ΔE 0.061
- Deep Sea Blue #015482 ΔE 0.061
- Dusk Blue #26538D ΔE 0.064
Use #243F79 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.