#4278BC
Closest named color: Windows Blue (#3778BF). oklch(56.8% 0.121 255.2), rgb(66, 120, 188).
Aa
Black text reads best on this color (4.64:1).
About this color
#4278BC is a medium-dark, moderately saturated blue. In OKLCH its lightness is 57%, its chroma 0.121 and its hue 255°. Its hue sits on the cool side of the wheel. The nearest named color is Windows Blue (#3778BF), ΔE 0.010 away. Black text reads best on it, at 4.64:1.
| Hue family | Blues |
| Lightness | medium-dark (57%) |
| Chroma | moderately saturated (0.121) |
| Temperature | cool |
| Nearest name | Windows Blue (#3778BF) |
| Black text | 4.64:1 |
| White text | 4.52:1 |
Values
| HEX | #4278BC |
| RGB | rgb(66, 120, 188) |
| HSL | hsl(213, 48%, 50%) |
| OKLCH | oklch(56.8% 0.121 255.2) |
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 #4278BC | 4.52:1 | AA | Lc -76.6 | Fine for body text |
| Black text on #4278BC | 4.64:1 | AA | Lc 32.9 | Non-text elements, placeholder text |
| #4278BC text on white | 4.52:1 | AA | Lc 71.2 | Content text, not long reading |
| #4278BC text on black | 4.64:1 | AA | Lc -30.5 | 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
#F2F6FA
oklch(97.1% 0.007 247.9)
-
Step 100
100
#E3EBF4
oklch(93.7% 0.015 251.2)
-
Step 200
200
#CCDBED
oklch(88.6% 0.03 253)
-
Step 300
300
#AAC3E4
oklch(81% 0.054 255.4)
-
Step 400
400
#7CA3D6
oklch(70.7% 0.087 255.4)
-
Step 500
500
#5A8CCB
oklch(63.2% 0.11 254.8)
-
Step 600
600 (this color)
#4278BC
oklch(56.8% 0.121 255.2)
-
Step 700
700
#30629F
oklch(49.2% 0.112 254.8)
-
Step 800
800
#295081
oklch(42.8% 0.093 255.2)
-
Step 900
900
#264367
oklch(37.8% 0.071 254.7)
-
Step 950
950
#17273C
oklch(27% 0.045 255.6)
#4278BC 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) | #5A7DBF | 0.031 |
| Deuteranopia (no green cones) | #4971BB | 0.019 |
| Tritanopia (no blue cones) | #008891 | 0.098 |
| Achromatopsia (no color) | #767676 | 0.121 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #4278BC
#4278BC
oklch(56.8% 0.121 255.2)
- #9F6B00
#9F6B00
oklch(56.8% 0.12 75.4)
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 #4278BC, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Windows Blue #3778BF ΔE 0.010
- Flat Blue #3C73A8 ΔE 0.033
- Steel Blue #4682B4 ΔE 0.034
- Nice Blue #107AB0 ΔE 0.037
- Cool Blue #4984B8 ΔE 0.038
- French Blue #436BAD ΔE 0.039
- Water Blue #0E87CC ΔE 0.046
- Muted Blue #3B719F ΔE 0.048
Use #4278BC 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.