#3666BB
Closest named color: Mid Blue (#276AB3). oklch(52.2% 0.144 260.9), rgb(54, 102, 187).
Aa
White text reads best on this color (5.56:1).
About this color
#3666BB is a medium-dark, vivid blue. In OKLCH its lightness is 52%, its chroma 0.144 and its hue 261°. Its hue sits on the cool side of the wheel. The nearest named color is Mid Blue (#276AB3), ΔE 0.021 away. White text reads best on it, at 5.56:1.
| Hue family | Blues |
| Lightness | medium-dark (52%) |
| Chroma | vivid (0.144) |
| Temperature | cool |
| Nearest name | Mid Blue (#276AB3) |
| Black text | 3.77:1 |
| White text | 5.56:1 |
Values
| HEX | #3666BB |
| RGB | rgb(54, 102, 187) |
| HSL | hsl(218, 55%, 47%) |
| OKLCH | oklch(52.2% 0.144 260.9) |
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 #3666BB | 5.56:1 | AA | Lc -82.8 | Fine for body text |
| Black text on #3666BB | 3.77:1 | AA large text | Lc 26.6 | Dividers and decoration only |
| #3666BB text on white | 5.56:1 | AA | Lc 77.5 | Fine for body text |
| #3666BB text on black | 3.77:1 | AA large text | Lc -24.3 | 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
#F2F6FC
oklch(97.2% 0.009 258.3)
-
Step 100
100
#E2EAF8
oklch(93.5% 0.021 261.8)
-
Step 200
200
#CBDAF3
oklch(88.5% 0.038 260.7)
-
Step 300
300
#A7C2EE
oklch(80.9% 0.069 260.1)
-
Step 400
400
#78A1E6
oklch(70.7% 0.111 260.5)
-
Step 500
500
#5688DF
oklch(63.2% 0.142 260.8)
-
Step 600
600
#3B6FCC
oklch(55.5% 0.155 261)
-
Step 700
700 (this color)
#3666BB
oklch(52.2% 0.144 260.9)
-
Step 800
800
#264C8F
oklch(42.6% 0.119 260.8)
-
Step 900
900
#244072
oklch(37.7% 0.092 261.1)
-
Step 950
950
#152643
oklch(27% 0.059 260.5)
#3666BB 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) | #3B6FBE | 0.026 |
| Deuteranopia (no green cones) | #2062B9 | 0.022 |
| Tritanopia (no blue cones) | #007A87 | 0.115 |
| Achromatopsia (no color) | #686868 | 0.144 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #3666BB
#3666BB
oklch(52.2% 0.144 260.9)
- #896100
#896100
oklch(52.1% 0.108 80.4)
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 #3666BB, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Mid Blue #276AB3 ΔE 0.021
- French Blue #436BAD ΔE 0.031
- Windows Blue #3778BF ΔE 0.050
- Flat Blue #3C73A8 ΔE 0.053
- Muted Blue #3B719F ΔE 0.060
- Royal Blue #4169E1 ΔE 0.061
- Dusky Blue #475F94 ΔE 0.062
- Nice Blue #107AB0 ΔE 0.063
Use #3666BB 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.