#4278CC
Closest named color: Windows Blue (#3778BF). oklch(57.7% 0.142 259), rgb(66, 120, 204).
Aa
Black text reads best on this color (4.79:1).
About this color
#4278CC is a medium-dark, vivid blue. In OKLCH its lightness is 58%, its chroma 0.142 and its hue 259°. Its hue sits on the cool side of the wheel. The nearest named color is Windows Blue (#3778BF), ΔE 0.023 away. Black text reads best on it, at 4.79:1.
| Hue family | Blues |
| Lightness | medium-dark (58%) |
| Chroma | vivid (0.142) |
| Temperature | cool |
| Nearest name | Windows Blue (#3778BF) |
| Black text | 4.79:1 |
| White text | 4.38:1 |
Values
| HEX | #4278CC |
| RGB | rgb(66, 120, 204) |
| HSL | hsl(217, 58%, 53%) |
| OKLCH | oklch(57.7% 0.142 259) |
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 #4278CC | 4.38:1 | AA large text | Lc -75.6 | Fine for body text |
| Black text on #4278CC | 4.79:1 | AA | Lc 34.0 | Non-text elements, placeholder text |
| #4278CC text on white | 4.38:1 | AA large text | Lc 70.1 | Content text, not long reading |
| #4278CC text on black | 4.79:1 | AA | Lc -31.6 | 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
#F2F6FB
oklch(97.2% 0.008 253.9)
-
Step 100
100
#E3EAF7
oklch(93.6% 0.019 263)
-
Step 200
200
#CBDAF1
oklch(88.4% 0.036 258.9)
-
Step 300
300
#A8C2EA
oklch(80.8% 0.064 258.9)
-
Step 400
400
#7AA2E0
oklch(70.8% 0.101 258.9)
-
Step 500
500
#5789D8
oklch(63.1% 0.131 259.2)
-
Step 600
600 (this color)
#4278CC
oklch(57.7% 0.142 259)
-
Step 700
700
#2E5FAA
oklch(49.2% 0.131 258.8)
-
Step 800
800
#274E8A
oklch(42.8% 0.109 258.8)
-
Step 900
900
#24416E
oklch(37.7% 0.085 258.9)
-
Step 950
950
#162641
oklch(27% 0.055 260.3)
#4278CC 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) | #517FCF | 0.026 |
| Deuteranopia (no green cones) | #3B73CA | 0.016 |
| Tritanopia (no blue cones) | #008B98 | 0.114 |
| Achromatopsia (no color) | #797979 | 0.142 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #4278CC
#4278CC
oklch(57.7% 0.142 259)
- #9F6F00
#9F6F00
oklch(57.6% 0.12 78.7)
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 #4278CC, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Windows Blue #3778BF ΔE 0.023
- Water Blue #0E87CC ΔE 0.045
- Cool Blue #4984B8 ΔE 0.051
- Steel Blue #4682B4 ΔE 0.052
- Royal Blue #4169E1 ΔE 0.054
- French Blue #436BAD ΔE 0.055
- Nice Blue #107AB0 ΔE 0.056
- Flat Blue #3C73A8 ΔE 0.057
Use #4278CC 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.