#3F66BB
Closest named color: Mid Blue (#276AB3). oklch(52.6% 0.141 263.7), rgb(63, 102, 187).
Aa
White text reads best on this color (5.48:1).
About this color
#3F66BB is a medium-dark, vivid blue. In OKLCH its lightness is 53%, its chroma 0.141 and its hue 264°. Its hue sits on the cool side of the wheel. The nearest named color is Mid Blue (#276AB3), ΔE 0.026 away. White text reads best on it, at 5.48:1.
| Hue family | Blues |
| Lightness | medium-dark (53%) |
| Chroma | vivid (0.141) |
| Temperature | cool |
| Nearest name | Mid Blue (#276AB3) |
| Black text | 3.82:1 |
| White text | 5.48:1 |
Values
| HEX | #3F66BB |
| RGB | rgb(63, 102, 187) |
| HSL | hsl(221, 50%, 49%) |
| OKLCH | oklch(52.6% 0.141 263.7) |
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 #3F66BB | 5.48:1 | AA | Lc -82.4 | Fine for body text |
| Black text on #3F66BB | 3.82:1 | AA large text | Lc 27.0 | Dividers and decoration only |
| #3F66BB text on white | 5.48:1 | AA | Lc 77.1 | Fine for body text |
| #3F66BB text on black | 3.82:1 | AA large text | Lc -24.7 | 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 600.
-
Step 50
50
#F2F5FB
oklch(97% 0.009 264.5)
-
Step 100
100
#E4EAF7
oklch(93.6% 0.019 266)
-
Step 200
200
#CDDAF1
oklch(88.6% 0.035 262)
-
Step 300
300
#ACC1EA
oklch(80.9% 0.063 263.7)
-
Step 400
400
#80A0E0
oklch(70.7% 0.101 263.6)
-
Step 500
500
#6087D8
oklch(63.1% 0.13 263.6)
-
Step 600
600 (this color)
#3F66BB
oklch(52.6% 0.141 263.7)
-
Step 700
700
#395DAA
oklch(49.2% 0.13 263.5)
-
Step 800
800
#2F4C8A
oklch(42.7% 0.109 263.6)
-
Step 900
900
#2A406E
oklch(37.8% 0.084 263.6)
-
Step 950
950
#192641
oklch(27.2% 0.054 263.7)
#3F66BB 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) | #3C6FBE | 0.024 |
| Deuteranopia (no green cones) | #2664B9 | 0.024 |
| Tritanopia (no blue cones) | #007A87 | 0.117 |
| Achromatopsia (no color) | #696969 | 0.141 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #3F66BB
#3F66BB
oklch(52.6% 0.141 263.7)
- #886400
#886400
oklch(52.6% 0.108 83.8)
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 #3F66BB, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Mid Blue #276AB3 ΔE 0.026
- French Blue #436BAD ΔE 0.029
- Windows Blue #3778BF ΔE 0.048
- Flat Blue #3C73A8 ΔE 0.052
- Iris #6258C4 ΔE 0.056
- Royal Blue #4169E1 ΔE 0.059
- Muted Blue #3B719F ΔE 0.059
- Dusky Blue #475F94 ΔE 0.062
Use #3F66BB 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.