#3778BB
Closest named color: Windows Blue (#3778BF). oklch(56.3% 0.124 251.5), rgb(55, 120, 187).
Aa
White text reads best on this color (4.59:1).
About this color
#3778BB is a medium-dark, moderately saturated blue. In OKLCH its lightness is 56%, its chroma 0.124 and its hue 252°. Its hue sits on the cool side of the wheel. The nearest named color is Windows Blue (#3778BF), ΔE 0.006 away. White text reads best on it, at 4.59:1.
| Hue family | Blues |
| Lightness | medium-dark (56%) |
| Chroma | moderately saturated (0.124) |
| Temperature | cool |
| Nearest name | Windows Blue (#3778BF) |
| Black text | 4.56:1 |
| White text | 4.59:1 |
Values
| HEX | #3778BB |
| RGB | rgb(55, 120, 187) |
| HSL | hsl(210, 55%, 47%) |
| OKLCH | oklch(56.3% 0.124 251.5) |
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 #3778BB | 4.59:1 | AA | Lc -77.1 | Fine for body text |
| Black text on #3778BB | 4.56:1 | AA | Lc 32.4 | Non-text elements, placeholder text |
| #3778BB text on white | 4.59:1 | AA | Lc 71.7 | Content text, not long reading |
| #3778BB text on black | 4.56:1 | AA | Lc -30.0 | 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
#E2EBF5
oklch(93.6% 0.017 250.8)
-
Step 200
200
#CBDBED
oklch(88.5% 0.03 251.3)
-
Step 300
300
#A7C4E4
oklch(81% 0.055 251.1)
-
Step 400
400
#77A4D7
oklch(70.6% 0.09 252.2)
-
Step 500
500
#528DCC
oklch(63.1% 0.114 251.5)
-
Step 600
600 (this color)
#3778BB
oklch(56.3% 0.124 251.5)
-
Step 700
700
#27639F
oklch(49.1% 0.114 251.3)
-
Step 800
800
#225181
oklch(42.7% 0.095 251.4)
-
Step 900
900
#214368
oklch(37.6% 0.075 252.2)
-
Step 950
950
#14283D
oklch(27.1% 0.047 251)
#3778BB 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) | #5A7CBE | 0.038 |
| Deuteranopia (no green cones) | #4770BA | 0.024 |
| Tritanopia (no blue cones) | #008891 | 0.094 |
| Achromatopsia (no color) | #757575 | 0.124 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #3778BB
#3778BB
oklch(56.3% 0.124 251.5)
- #A06700
#A06700
oklch(56.2% 0.121 71.6)
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 #3778BB, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Windows Blue #3778BF ΔE 0.006
- Nice Blue #107AB0 ΔE 0.029
- Flat Blue #3C73A8 ΔE 0.030
- Steel Blue #4682B4 ΔE 0.037
- French Blue #436BAD ΔE 0.038
- Cool Blue #4984B8 ΔE 0.041
- Mid Blue #276AB3 ΔE 0.044
- Muted Blue #3B719F ΔE 0.044
Use #3778BB 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.