#577BCB
Closest named color: Windows Blue (#3778BF). oklch(59.3% 0.129 264.5), rgb(87, 123, 203).
Aa
Black text reads best on this color (5.10:1).
About this color
#577BCB is a medium-dark, moderately saturated blue. In OKLCH its lightness is 59%, its chroma 0.129 and its hue 265°. Its hue sits on the cool side of the wheel. The nearest named color is Windows Blue (#3778BF), ΔE 0.039 away. Black text reads best on it, at 5.10:1.
| Hue family | Blues |
| Lightness | medium-dark (59%) |
| Chroma | moderately saturated (0.129) |
| Temperature | cool |
| Nearest name | Windows Blue (#3778BF) |
| Black text | 5.10:1 |
| White text | 4.11:1 |
Values
| HEX | #577BCB |
| RGB | rgb(87, 123, 203) |
| HSL | hsl(221, 53%, 57%) |
| OKLCH | oklch(59.3% 0.129 264.5) |
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 #577BCB | 4.11:1 | AA large text | Lc -73.6 | Content text, not long reading |
| Black text on #577BCB | 5.10:1 | AA | Lc 36.0 | Non-text elements, placeholder text |
| #577BCB text on white | 4.11:1 | AA large text | Lc 68.1 | Content text, not long reading |
| #577BCB text on black | 5.10:1 | AA | Lc -33.5 | 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 600.
-
Step 50
50
#F3F5FB
oklch(97% 0.008 271.3)
-
Step 100
100
#E4EAF6
oklch(93.6% 0.017 264.5)
-
Step 200
200
#CFD9EF
oklch(88.4% 0.032 266.1)
-
Step 300
300
#AEC1E7
oklch(80.9% 0.058 264.2)
-
Step 400
400
#84A0DB
oklch(70.7% 0.092 264.6)
-
Step 500
500
#6587D2
oklch(63.1% 0.12 264.7)
-
Step 600
600 (this color)
#577BCB
oklch(59.3% 0.129 264.5)
-
Step 700
700
#3E5DA4
oklch(49.1% 0.12 264.6)
-
Step 800
800
#334C85
oklch(42.6% 0.1 264.7)
-
Step 900
900
#2D406B
oklch(37.7% 0.078 264.9)
-
Step 950
950
#1A263F
oklch(27.1% 0.05 263.9)
#577BCB 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) | #5983CE | 0.022 |
| Deuteranopia (no green cones) | #4A78C9 | 0.018 |
| Tritanopia (no blue cones) | #008D99 | 0.116 |
| Achromatopsia (no color) | #7D7D7D | 0.129 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #577BCB
#577BCB
oklch(59.3% 0.129 264.5)
- #A07700
#A07700
oklch(59.4% 0.122 84.4)
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 #577BCB, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Windows Blue #3778BF ΔE 0.039
- Cool Blue #4984B8 ΔE 0.045
- Steel Blue #4682B4 ΔE 0.048
- Water Blue #0E87CC ΔE 0.052
- Off Blue #5684AE ΔE 0.057
- Dark Sky Blue #448EE4 ΔE 0.057
- Soft Blue #6488EA ΔE 0.058
- Faded Blue #658CBB ΔE 0.062
Use #577BCB 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.