#00509B
Closest named color: Cobalt (#1E488F). oklch(43.5% 0.139 254.2), rgb(0, 80, 155).
Aa
White text reads best on this color (8.01:1).
About this color
#00509B is a dark, moderately saturated blue. In OKLCH its lightness is 44%, its chroma 0.139 and its hue 254°. Its hue sits on the cool side of the wheel. The nearest named color is Cobalt (#1E488F), ΔE 0.028 away. White text reads best on it, at 8.01:1.
| Hue family | Blues |
| Lightness | dark (44%) |
| Chroma | moderately saturated (0.139) |
| Temperature | cool |
| Nearest name | Cobalt (#1E488F) |
| Black text | 2.62:1 |
| White text | 8.01:1 |
Values
| HEX | #00509B |
| RGB | rgb(0, 80, 155) |
| HSL | hsl(209, 100%, 30%) |
| OKLCH | oklch(43.5% 0.139 254.2) |
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 #00509B | 8.01:1 | AAA | Lc -91.8 | Preferred for body text |
| Black text on #00509B | 2.62:1 | Fails | Lc 16.9 | Dividers and decoration only |
| #00509B text on white | 8.01:1 | AAA | Lc 87.1 | Fine for body text |
| #00509B text on black | 2.62:1 | Fails | Lc -15.0 | Dividers and decoration only |
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
#F1F6FD
oklch(97.1% 0.011 256.7)
-
Step 100
100
#DFEBFA
oklch(93.6% 0.024 254)
-
Step 200
200
#C5DBF7
oklch(88.4% 0.045 254.5)
-
Step 300
300
#9DC4F5
oklch(81% 0.081 254.4)
-
Step 400
400
#64A3F0
oklch(70.6% 0.131 254.3)
-
Step 500
500
#358AEB
oklch(63.1% 0.167 254.3)
-
Step 600
600
#0072D8
oklch(55.7% 0.178 254.2)
-
Step 700
700
#005FB6
oklch(49% 0.157 254.2)
-
Step 800
800 (this color)
#00509B
oklch(43.5% 0.139 254.2)
-
Step 900
900
#0D4179
oklch(37.6% 0.109 254.3)
-
Step 950
950
#0B2747
oklch(27.1% 0.068 254.1)
#00509B 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) | #24579E | 0.030 |
| Deuteranopia (no green cones) | #004B9A | 0.014 |
| Tritanopia (no blue cones) | #00626E | 0.102 |
| Achromatopsia (no color) | #505050 | 0.139 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #00509B
#00509B
oklch(43.5% 0.139 254.2)
- #6F4800
#6F4800
oklch(43.5% 0.092 73.8)
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 #00509B, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cobalt #1E488F ΔE 0.028
- Dusk Blue #26538D ΔE 0.032
- Light Navy #155084 ΔE 0.038
- Deep Sea Blue #015482 ΔE 0.045
- Light Navy Blue #2E5A88 ΔE 0.055
- Denim Blue #3B5B92 ΔE 0.058
- Twilight Blue #0A437A ΔE 0.063
- Sapphire #2138AB ΔE 0.065
Use #00509B 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.