#5B66CB
Closest named color: Dark Periwinkle (#665FD1). oklch(55.3% 0.155 275.5), rgb(91, 102, 203).
Aa
White text reads best on this color (4.99:1).
About this color
#5B66CB is a medium-dark, vivid blue. In OKLCH its lightness is 55%, its chroma 0.155 and its hue 275°. 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 4.99:1.
| Hue family | Blues |
| Lightness | medium-dark (55%) |
| Chroma | vivid (0.155) |
| Temperature | cool |
| Nearest name | Dark Periwinkle (#665FD1) |
| Black text | 4.20:1 |
| White text | 4.99:1 |
Values
| HEX | #5B66CB |
| RGB | rgb(91, 102, 203) |
| HSL | hsl(234, 52%, 58%) |
| OKLCH | oklch(55.3% 0.155 275.5) |
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 #5B66CB | 4.99:1 | AA | Lc -79.7 | Fine for body text |
| Black text on #5B66CB | 4.20:1 | AA large text | Lc 29.8 | Dividers and decoration only |
| #5B66CB text on white | 4.99:1 | AA | Lc 74.3 | Content text, not long reading |
| #5B66CB text on black | 4.20:1 | AA large text | Lc -27.4 | 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
#F3F5FC
oklch(97.1% 0.01 273.4)
-
Step 100
100
#E6E9F8
oklch(93.6% 0.02 276.9)
-
Step 200
200
#D1D8F3
oklch(88.5% 0.038 274.1)
-
Step 300
300
#B3BEEE
oklch(80.9% 0.069 274.7)
-
Step 400
400
#8D9AE6
oklch(70.6% 0.112 275.7)
-
Step 500
500
#7280DE
oklch(63.1% 0.141 275.2)
-
Step 600
600 (this color)
#5B66CB
oklch(55.3% 0.155 275.5)
-
Step 700
700
#4C55B1
oklch(49.1% 0.145 275.5)
-
Step 800
800
#3E468F
oklch(42.7% 0.119 275.4)
-
Step 900
900
#343B72
oklch(37.6% 0.094 275.5)
-
Step 950
950
#1F2343
oklch(27% 0.059 276.3)
#5B66CB 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) | #3374CF | 0.050 |
| Deuteranopia (no green cones) | #236BC9 | 0.054 |
| Tritanopia (no blue cones) | #207D8F | 0.137 |
| Achromatopsia (no color) | #6F6F6F | 0.155 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #5B66CB
#5B66CB
oklch(55.3% 0.155 275.5)
- #877100
#877100
oklch(55.3% 0.114 95.5)
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 #5B66CB, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Dark Periwinkle #665FD1 ΔE 0.024
- Slate Blue #6A5ACD ΔE 0.034
- Iris #6258C4 ΔE 0.035
- Light Indigo #6D5ACF ΔE 0.037
- Royal Blue #4169E1 ΔE 0.044
- Warm Blue #4B57DB ΔE 0.052
- French Blue #436BAD ΔE 0.059
- Windows Blue #3778BF ΔE 0.062
Use #5B66CB 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.