#646FBF
Closest named color: Windows Blue (#3778BF). oklch(57% 0.123 275.8), rgb(100, 111, 191).
Aa
White text reads best on this color (4.59:1).
About this color
#646FBF is a medium-dark, moderately saturated blue. In OKLCH its lightness is 57%, its chroma 0.123 and its hue 276°. Its hue sits on the cool side of the wheel. The nearest named color is Windows Blue (#3778BF), ΔE 0.051 away. White text reads best on it, at 4.59:1.
| Hue family | Blues |
| Lightness | medium-dark (57%) |
| Chroma | moderately saturated (0.123) |
| Temperature | cool |
| Nearest name | Windows Blue (#3778BF) |
| Black text | 4.56:1 |
| White text | 4.59:1 |
Values
| HEX | #646FBF |
| RGB | rgb(100, 111, 191) |
| HSL | hsl(233, 42%, 57%) |
| OKLCH | oklch(57% 0.123 275.8) |
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 #646FBF | 4.59:1 | AA | Lc -77.3 | Fine for body text |
| Black text on #646FBF | 4.56:1 | AA | Lc 32.3 | Non-text elements, placeholder text |
| #646FBF text on white | 4.59:1 | AA | Lc 71.8 | Content text, not long reading |
| #646FBF text on black | 4.56:1 | AA | Lc -29.9 | 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
#F4F5FB
oklch(97.1% 0.008 278.6)
-
Step 100
100
#E7E9F5
oklch(93.6% 0.016 278.5)
-
Step 200
200
#D3D8EE
oklch(88.5% 0.031 275.6)
-
Step 300
300
#B6BEE5
oklch(80.8% 0.056 276)
-
Step 400
400
#919CD8
oklch(70.7% 0.089 275.9)
-
Step 500
500
#7783CE
oklch(63.2% 0.114 275.8)
-
Step 600
600 (this color)
#646FBF
oklch(57% 0.123 275.8)
-
Step 700
700
#5059A1
oklch(49.2% 0.115 276)
-
Step 800
800
#414982
oklch(42.7% 0.095 275.6)
-
Step 900
900
#373D69
oklch(37.6% 0.075 276.3)
-
Step 950
950
#20243D
oklch(26.9% 0.047 275.9)
#646FBF 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) | #5079C2 | 0.033 |
| Deuteranopia (no green cones) | #4872BD | 0.034 |
| Tritanopia (no blue cones) | #42808E | 0.109 |
| Achromatopsia (no color) | #757575 | 0.124 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #646FBF
#646FBF
oklch(57% 0.123 275.8)
- #8C7600
#8C7600
oklch(57% 0.117 96)
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 #646FBF, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Windows Blue #3778BF ΔE 0.051
- French Blue #436BAD ΔE 0.052
- Dark Periwinkle #665FD1 ΔE 0.052
- Slate Blue #6A5ACD ΔE 0.060
- Iris #6258C4 ΔE 0.061
- Light Indigo #6D5ACF ΔE 0.061
- Flat Blue #3C73A8 ΔE 0.062
- Steel Blue #4682B4 ΔE 0.065
Use #646FBF 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.