#6566DD
Closest named color: Dark Periwinkle (#665FD1). oklch(57.2% 0.177 278.8), rgb(101, 102, 221).
Aa
White text reads best on this color (4.66:1).
About this color
#6566DD is a medium-dark, vivid blue. In OKLCH its lightness is 57%, its chroma 0.177 and its hue 279°. Its hue sits on the cool side of the wheel. The nearest named color is Dark Periwinkle (#665FD1), ΔE 0.024 away. White text reads best on it, at 4.66:1.
| Hue family | Blues |
| Lightness | medium-dark (57%) |
| Chroma | vivid (0.177) |
| Temperature | cool |
| Nearest name | Dark Periwinkle (#665FD1) |
| Black text | 4.49:1 |
| White text | 4.66:1 |
Values
| HEX | #6566DD |
| RGB | rgb(101, 102, 221) |
| HSL | hsl(240, 64%, 63%) |
| OKLCH | oklch(57.2% 0.177 278.8) |
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 #6566DD | 4.66:1 | AA | Lc -77.6 | Fine for body text |
| Black text on #6566DD | 4.49:1 | AA large text | Lc 32.0 | Non-text elements, placeholder text |
| #6566DD text on white | 4.66:1 | AA | Lc 72.1 | Content text, not long reading |
| #6566DD text on black | 4.49:1 | AA large text | Lc -29.6 | 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
#F4F5FD
oklch(97.2% 0.011 280.5)
-
Step 100
100
#E6E9FA
oklch(93.7% 0.023 277.9)
-
Step 200
200
#D2D7F7
oklch(88.5% 0.044 278.4)
-
Step 300
300
#B5BCF4
oklch(80.9% 0.079 278.9)
-
Step 400
400
#9097EF
oklch(70.7% 0.128 279.1)
-
Step 500
500
#767BE9
oklch(63.1% 0.162 278.7)
-
Step 600
600 (this color)
#6566DD
oklch(57.2% 0.177 278.8)
-
Step 700
700
#504FBB
oklch(49% 0.166 278.8)
-
Step 800
800
#424297
oklch(42.8% 0.136 279)
-
Step 900
900
#373978
oklch(37.8% 0.105 278.7)
-
Step 950
950
#202246
oklch(27.1% 0.066 278.6)
#6566DD 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) | #1C79E1 | 0.073 |
| Deuteranopia (no green cones) | #006FDA | 0.077 |
| Tritanopia (no blue cones) | #2B8198 | 0.153 |
| Achromatopsia (no color) | #747474 | 0.178 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #6566DD
#6566DD
oklch(57.2% 0.177 278.8)
- #8A7800
#8A7800
oklch(57.2% 0.118 98.7)
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 #6566DD, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Dark Periwinkle #665FD1 ΔE 0.024
- Light Indigo #6D5ACF ΔE 0.035
- Slate Blue #6A5ACD ΔE 0.036
- Medium Slate Blue #7B68EE ΔE 0.042
- Royal Blue #4169E1 ΔE 0.043
- Iris #6258C4 ΔE 0.049
- Neon Blue #4361EE ΔE 0.052
- Warm Blue #4B57DB ΔE 0.054
Use #6566DD 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.