#6366CB
Closest named color: Dark Periwinkle (#665FD1). oklch(55.9% 0.153 278.9), rgb(99, 102, 203).
Aa
White text reads best on this color (4.89:1).
About this color
#6366CB is a medium-dark, vivid blue. In OKLCH its lightness is 56%, its chroma 0.153 and its hue 279°. Its hue sits on the cool side of the wheel. The nearest named color is Dark Periwinkle (#665FD1), ΔE 0.020 away. White text reads best on it, at 4.89:1.
| Hue family | Blues |
| Lightness | medium-dark (56%) |
| Chroma | vivid (0.153) |
| Temperature | cool |
| Nearest name | Dark Periwinkle (#665FD1) |
| Black text | 4.29:1 |
| White text | 4.89:1 |
Values
| HEX | #6366CB |
| RGB | rgb(99, 102, 203) |
| HSL | hsl(238, 50%, 59%) |
| OKLCH | oklch(55.9% 0.153 278.9) |
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 #6366CB | 4.89:1 | AA | Lc -79.1 | Fine for body text |
| Black text on #6366CB | 4.29:1 | AA large text | Lc 30.4 | Non-text elements, placeholder text |
| #6366CB text on white | 4.89:1 | AA | Lc 73.7 | Content text, not long reading |
| #6366CB text on black | 4.29:1 | AA large text | Lc -28.0 | 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
#F4F5FC
oklch(97.1% 0.009 279.7)
-
Step 100
100
#E7E9F7
oklch(93.7% 0.019 279.5)
-
Step 200
200
#D3D7F3
oklch(88.5% 0.039 279.1)
-
Step 300
300
#B6BDED
oklch(80.9% 0.068 278.3)
-
Step 400
400
#9299E4
oklch(70.7% 0.11 279.1)
-
Step 500
500
#787EDD
oklch(63.1% 0.141 278.8)
-
Step 600
600 (this color)
#6366CB
oklch(55.9% 0.153 278.9)
-
Step 700
700
#5253AF
oklch(49% 0.143 279.3)
-
Step 800
800
#43458E
oklch(42.8% 0.118 279)
-
Step 900
900
#383B71
oklch(37.8% 0.091 278.7)
-
Step 950
950
#212342
oklch(27.1% 0.057 279.1)
#6366CB 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) | #3675CF | 0.057 |
| Deuteranopia (no green cones) | #2B6DC9 | 0.060 |
| Tritanopia (no blue cones) | #387C8F | 0.133 |
| Achromatopsia (no color) | #717171 | 0.153 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #6366CB
#6366CB
oklch(55.9% 0.153 278.9)
- #857400
#857400
oklch(55.8% 0.116 99)
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 #6366CB, closest first.
No curated palette has a color within ΔE 0.04 of #6366CB.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Dark Periwinkle #665FD1 ΔE 0.020
- Slate Blue #6A5ACD ΔE 0.030
- Light Indigo #6D5ACF ΔE 0.032
- Iris #6258C4 ΔE 0.035
- Royal Blue #4169E1 ΔE 0.051
- Warm Blue #4B57DB ΔE 0.059
- Medium Slate Blue #7B68EE ΔE 0.065
- French Blue #436BAD ΔE 0.065
Use #6366CB 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.