#243F99
Closest named color: Cobalt (#1E488F). oklch(40.5% 0.151 266.7), rgb(36, 63, 153).
Aa
White text reads best on this color (9.34:1).
About this color
#243F99 is a dark, vivid blue. In OKLCH its lightness is 41%, its chroma 0.151 and its hue 267°. Its hue sits on the cool side of the wheel. The nearest named color is Cobalt (#1E488F), ΔE 0.030 away. White text reads best on it, at 9.34:1.
| Hue family | Blues |
| Lightness | dark (41%) |
| Chroma | vivid (0.151) |
| Temperature | cool |
| Nearest name | Cobalt (#1E488F) |
| Black text | 2.24:1 |
| White text | 9.34:1 |
Values
| HEX | #243F99 |
| RGB | rgb(36, 63, 153) |
| HSL | hsl(226, 62%, 37%) |
| OKLCH | oklch(40.5% 0.151 266.7) |
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 #243F99 | 9.34:1 | AAA | Lc -95.4 | Preferred for body text |
| Black text on #243F99 | 2.24:1 | Fails | Lc 12.9 | Not readable |
| #243F99 text on white | 9.34:1 | AAA | Lc 91.1 | Preferred for body text |
| #243F99 text on black | 2.24:1 | Fails | Lc -11.2 | 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 800.
-
Step 50
50
#F2F5FE
oklch(97% 0.012 271.3)
-
Step 100
100
#E2EAFC
oklch(93.6% 0.026 266.6)
-
Step 200
200
#CAD9FB
oklch(88.5% 0.05 266.5)
-
Step 300
300
#A7C0FA
oklch(81% 0.087 266.4)
-
Step 400
400
#789CF8
oklch(70.6% 0.141 266.7)
-
Step 500
500
#5880F5
oklch(63% 0.18 267)
-
Step 600
600
#3F66E4
oklch(55.5% 0.196 266.8)
-
Step 700
700
#3254C6
oklch(49.1% 0.182 266.8)
-
Step 800
800 (this color)
#243F99
oklch(40.5% 0.151 266.7)
-
Step 900
900
#253C7F
oklch(37.8% 0.117 266.5)
-
Step 950
950
#16244A
oklch(27.1% 0.073 266.4)
#243F99 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) | #004C9C | 0.036 |
| Deuteranopia (no green cones) | #004197 | 0.022 |
| Tritanopia (no blue cones) | #005565 | 0.119 |
| Achromatopsia (no color) | #474747 | 0.151 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #243F99
#243F99
oklch(40.5% 0.151 266.7)
- #5C4500
#5C4500
oklch(40.4% 0.083 86.9)
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 #243F99, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cobalt #1E488F ΔE 0.030
- Sapphire #2138AB ΔE 0.034
- Blueberry #464196 ΔE 0.047
- Dark Slate Blue #483D8B ΔE 0.054
- Twilight Blue #0A437A ΔE 0.058
- Dusk Blue #26538D ΔE 0.061
- Light Navy #155084 ΔE 0.062
- Blue Blue #2242C7 ΔE 0.075
Use #243F99 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.