#517DCB
Closest named color: Windows Blue (#3778BF). oklch(59.4% 0.129 261.1), rgb(81, 125, 203).
Aa
Black text reads best on this color (5.14:1).
About this color
#517DCB is a medium-dark, moderately saturated blue. In OKLCH its lightness is 59%, its chroma 0.129 and its hue 261°. Its hue sits on the cool side of the wheel. The nearest named color is Windows Blue (#3778BF), ΔE 0.035 away. Black text reads best on it, at 5.14:1.
| Hue family | Blues |
| Lightness | medium-dark (59%) |
| Chroma | moderately saturated (0.129) |
| Temperature | cool |
| Nearest name | Windows Blue (#3778BF) |
| Black text | 5.14:1 |
| White text | 4.08:1 |
Values
| HEX | #517DCB |
| RGB | rgb(81, 125, 203) |
| HSL | hsl(218, 54%, 56%) |
| OKLCH | oklch(59.4% 0.129 261.1) |
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 #517DCB | 4.08:1 | AA large text | Lc -73.3 | Content text, not long reading |
| Black text on #517DCB | 5.14:1 | AA | Lc 36.3 | Non-text elements, placeholder text |
| #517DCB text on white | 4.08:1 | AA large text | Lc 67.8 | Content text, not long reading |
| #517DCB text on black | 5.14:1 | AA | Lc -33.9 | Non-text elements, placeholder text |
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 500.
-
Step 50
50
#F2F6FB
oklch(97.2% 0.008 253.9)
-
Step 100
100
#E3EAF7
oklch(93.6% 0.019 263)
-
Step 200
200
#CCDAF1
oklch(88.5% 0.035 260.4)
-
Step 300
300
#AAC2EA
oklch(81% 0.063 260.6)
-
Step 400
400
#7DA1E0
oklch(70.7% 0.101 261.2)
-
Step 500
500 (this color)
#517DCB
oklch(59.4% 0.129 261.1)
-
Step 600
600
#4271C5
oklch(55.8% 0.14 261.1)
-
Step 700
700
#335EAA
oklch(49.1% 0.131 260.9)
-
Step 800
800
#2B4D8A
oklch(42.7% 0.109 261.1)
-
Step 900
900
#27416E
oklch(37.8% 0.084 260.7)
-
Step 950
950
#172640
oklch(27% 0.053 260.8)
#517DCB 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) | #5C84CE | 0.024 |
| Deuteranopia (no green cones) | #4B78C9 | 0.016 |
| Tritanopia (no blue cones) | #008F9A | 0.112 |
| Achromatopsia (no color) | #7E7E7E | 0.129 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #517DCB
#517DCB
oklch(59.4% 0.129 261.1)
- #A37500
#A37500
oklch(59.3% 0.123 81.1)
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 #517DCB, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Windows Blue #3778BF ΔE 0.035
- Cool Blue #4984B8 ΔE 0.040
- Steel Blue #4682B4 ΔE 0.043
- Water Blue #0E87CC ΔE 0.045
- Dark Sky Blue #448EE4 ΔE 0.053
- Off Blue #5684AE ΔE 0.054
- Soft Blue #6488EA ΔE 0.058
- Dusty Blue #5A86AD ΔE 0.059
Use #517DCB 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.