#646FDF
Closest named color: Dark Periwinkle (#665FD1). oklch(59% 0.168 275.7), rgb(100, 111, 223).
Aa
Black text reads best on this color (4.88:1).
About this color
#646FDF is a medium-dark, vivid blue. In OKLCH its lightness is 59%, its chroma 0.168 and its hue 276°. Its hue sits on the cool side of the wheel. The nearest named color is Dark Periwinkle (#665FD1), ΔE 0.042 away. Black text reads best on it, at 4.88:1.
| Hue family | Blues |
| Lightness | medium-dark (59%) |
| Chroma | vivid (0.168) |
| Temperature | cool |
| Nearest name | Dark Periwinkle (#665FD1) |
| Black text | 4.88:1 |
| White text | 4.30:1 |
Values
| HEX | #646FDF |
| RGB | rgb(100, 111, 223) |
| HSL | hsl(235, 66%, 63%) |
| OKLCH | oklch(59% 0.168 275.7) |
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 #646FDF | 4.30:1 | AA large text | Lc -75.0 | Content text, not long reading |
| Black text on #646FDF | 4.88:1 | AA | Lc 34.6 | Non-text elements, placeholder text |
| #646FDF text on white | 4.30:1 | AA large text | Lc 69.5 | Content text, not long reading |
| #646FDF text on black | 4.88:1 | AA | Lc -32.2 | 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
#F3F5FC
oklch(97.1% 0.01 273.4)
-
Step 100
100
#E5E9F9
oklch(93.6% 0.022 274.7)
-
Step 200
200
#D1D7F6
oklch(88.4% 0.043 276.8)
-
Step 300
300
#B3BDF2
oklch(80.9% 0.076 276.3)
-
Step 400
400
#8C99EC
oklch(70.7% 0.122 276)
-
Step 500
500
#717EE6
oklch(63.2% 0.155 275.7)
-
Step 600
600 (this color)
#646FDF
oklch(59% 0.168 275.7)
-
Step 700
700
#4B53B7
oklch(49.1% 0.156 275.6)
-
Step 800
800
#3D4494
oklch(42.6% 0.13 275.7)
-
Step 900
900
#343A76
oklch(37.6% 0.101 276.1)
-
Step 950
950
#1E2345
oklch(27.1% 0.063 275.1)
#646FDF 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) | #357FE3 | 0.056 |
| Deuteranopia (no green cones) | #2175DD | 0.061 |
| Tritanopia (no blue cones) | #22889C | 0.149 |
| Achromatopsia (no color) | #7A7A7A | 0.169 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #646FDF
#646FDF
oklch(59% 0.168 275.7)
- #937C00
#937C00
oklch(59% 0.121 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 #646FDF, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Dark Periwinkle #665FD1 ΔE 0.042
- Medium Slate Blue #7B68EE ΔE 0.043
- Cornflower #6A79F7 ΔE 0.043
- Royal Blue #4169E1 ΔE 0.046
- Light Indigo #6D5ACF ΔE 0.053
- Slate Blue #6A5ACD ΔE 0.055
- Neon Blue #4361EE ΔE 0.061
- Soft Blue #6488EA ΔE 0.064
Use #646FDF 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.