#3666B4
Closest named color: Mid Blue (#276AB3). oklch(51.7% 0.134 259.6), rgb(54, 102, 180).
Aa
White text reads best on this color (5.65:1).
About this color
#3666B4 is a medium-dark, moderately saturated blue. In OKLCH its lightness is 52%, its chroma 0.134 and its hue 260°. Its hue sits on the cool side of the wheel. The nearest named color is Mid Blue (#276AB3), ΔE 0.015 away. White text reads best on it, at 5.65:1.
| Hue family | Blues |
| Lightness | medium-dark (52%) |
| Chroma | moderately saturated (0.134) |
| Temperature | cool |
| Nearest name | Mid Blue (#276AB3) |
| Black text | 3.71:1 |
| White text | 5.65:1 |
Values
| HEX | #3666B4 |
| RGB | rgb(54, 102, 180) |
| HSL | hsl(217, 54%, 46%) |
| OKLCH | oklch(51.7% 0.134 259.6) |
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 #3666B4 | 5.65:1 | AA | Lc -83.2 | Fine for body text |
| Black text on #3666B4 | 3.71:1 | AA large text | Lc 26.1 | Dividers and decoration only |
| #3666B4 text on white | 5.65:1 | AA | Lc 78.0 | Fine for body text |
| #3666B4 text on black | 3.71:1 | AA large text | Lc -23.8 | Dividers and decoration only |
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 700.
-
Step 50
50
#F2F6FB
oklch(97.2% 0.008 253.9)
-
Step 100
100
#E3EAF7
oklch(93.6% 0.019 263)
-
Step 200
200
#CBDAF2
oklch(88.5% 0.037 259.8)
-
Step 300
300
#A8C2EB
oklch(80.9% 0.065 259.4)
-
Step 400
400
#7AA1E1
oklch(70.6% 0.104 260)
-
Step 500
500
#5789D9
oklch(63.1% 0.133 259.4)
-
Step 600
600
#3C71C6
oklch(55.6% 0.144 259.5)
-
Step 700
700 (this color)
#3666B4
oklch(51.7% 0.134 259.6)
-
Step 800
800
#274D8B
oklch(42.6% 0.112 259.7)
-
Step 900
900
#24416F
oklch(37.7% 0.087 259.3)
-
Step 950
950
#162641
oklch(27% 0.055 260.3)
#3666B4 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) | #406DB7 | 0.023 |
| Deuteranopia (no green cones) | #2B62B2 | 0.016 |
| Tritanopia (no blue cones) | #007884 | 0.107 |
| Achromatopsia (no color) | #676767 | 0.134 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #3666B4
#3666B4
oklch(51.7% 0.134 259.6)
- #886000
#886000
oklch(51.8% 0.107 80.2)
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 #3666B4, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Mid Blue #276AB3 ΔE 0.015
- French Blue #436BAD ΔE 0.024
- Flat Blue #3C73A8 ΔE 0.046
- Windows Blue #3778BF ΔE 0.051
- Muted Blue #3B719F ΔE 0.051
- Dusky Blue #475F94 ΔE 0.052
- Denim Blue #3B5B92 ΔE 0.057
- Nice Blue #107AB0 ΔE 0.059
Use #3666B4 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.