#3778BF
Named color: Windows Blue. oklch(56.5% 0.129 252.8), rgb(55, 120, 191).
Aa
Black text reads best on this color (4.60:1).
About this color
#3778BF is a medium-dark, moderately saturated blue. In OKLCH its lightness is 56%, its chroma 0.129 and its hue 253°. Its hue sits on the cool side of the wheel. It is the named color Windows Blue. Black text reads best on it, at 4.60:1.
| Hue family | Blues |
| Lightness | medium-dark (56%) |
| Chroma | moderately saturated (0.129) |
| Temperature | cool |
| Nearest name | Windows Blue |
| Black text | 4.60:1 |
| White text | 4.56:1 |
Values
| HEX | #3778BF |
| RGB | rgb(55, 120, 191) |
| HSL | hsl(211, 55%, 48%) |
| OKLCH | oklch(56.5% 0.129 252.8) |
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 #3778BF | 4.56:1 | AA | Lc -76.9 | Fine for body text |
| Black text on #3778BF | 4.60:1 | AA | Lc 32.7 | Non-text elements, placeholder text |
| #3778BF text on white | 4.56:1 | AA | Lc 71.4 | Content text, not long reading |
| #3778BF text on black | 4.60:1 | AA | Lc -30.3 | 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
#E2EBF5
oklch(93.6% 0.017 250.8)
-
Step 200
200
#CBDBEE
oklch(88.5% 0.031 252.7)
-
Step 300
300
#A7C4E6
oklch(81% 0.058 252.6)
-
Step 400
400
#76A4D9
oklch(70.6% 0.093 252.6)
-
Step 500
500
#528CCF
oklch(63% 0.119 253.2)
-
Step 600
600 (this color)
#3778BF
oklch(56.5% 0.129 252.8)
-
Step 700
700
#2662A2
oklch(49% 0.12 252.8)
-
Step 800
800
#215083
oklch(42.6% 0.099 252.8)
-
Step 900
900
#214369
oklch(37.7% 0.077 252.8)
-
Step 950
950
#14273E
oklch(26.9% 0.05 254.1)
#3778BF 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) | #587DC2 | 0.037 |
| Deuteranopia (no green cones) | #4370BE | 0.023 |
| Tritanopia (no blue cones) | #008992 | 0.100 |
| Achromatopsia (no color) | #767676 | 0.129 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #3778BF
#3778BF
oklch(56.5% 0.129 252.8)
- #A06900
#A06900
oklch(56.6% 0.12 73.3)
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 #3778BF, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Nice Blue #107AB0 ΔE 0.034
- Flat Blue #3C73A8 ΔE 0.036
- Steel Blue #4682B4 ΔE 0.040
- French Blue #436BAD ΔE 0.041
- Water Blue #0E87CC ΔE 0.043
- Cool Blue #4984B8 ΔE 0.043
- Mid Blue #276AB3 ΔE 0.045
- Muted Blue #3B719F ΔE 0.050
Use #3778BF 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.