#665EF0
Closest named color: Medium Slate Blue (#7B68EE). oklch(57.3% 0.212 279.8), rgb(102, 94, 240).
Aa
White text reads best on this color (4.74:1).
About this color
#665EF0 is a medium-dark, vivid blue. In OKLCH its lightness is 57%, its chroma 0.212 and its hue 280°. Its hue sits on the cool side of the wheel. The nearest named color is Medium Slate Blue (#7B68EE), ΔE 0.041 away. White text reads best on it, at 4.74:1.
| Hue family | Blues |
| Lightness | medium-dark (57%) |
| Chroma | vivid (0.212) |
| Temperature | cool |
| Nearest name | Medium Slate Blue (#7B68EE) |
| Black text | 4.42:1 |
| White text | 4.74:1 |
Values
| HEX | #665EF0 |
| RGB | rgb(102, 94, 240) |
| HSL | hsl(243, 83%, 65%) |
| OKLCH | oklch(57.3% 0.212 279.8) |
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 #665EF0 | 4.74:1 | AA | Lc -77.9 | Fine for body text |
| Black text on #665EF0 | 4.42:1 | AA large text | Lc 31.6 | Non-text elements, placeholder text |
| #665EF0 text on white | 4.74:1 | AA | Lc 72.5 | Content text, not long reading |
| #665EF0 text on black | 4.42:1 | AA large text | Lc -29.2 | 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
#F3F5FE
oklch(97.1% 0.012 276.1)
-
Step 100
100
#E6E8FD
oklch(93.6% 0.028 281.5)
-
Step 200
200
#D1D6FC
oklch(88.4% 0.053 279.4)
-
Step 300
300
#B4BAFE
oklch(80.9% 0.096 280.1)
-
Step 400
400
#8F94FD
oklch(70.8% 0.152 279.7)
-
Step 500
500
#7674FB
oklch(63% 0.196 279.8)
-
Step 600
600 (this color)
#665EF0
oklch(57.3% 0.212 279.8)
-
Step 700
700
#5147CB
oklch(49% 0.196 279.7)
-
Step 800
800
#423BA4
oklch(42.6% 0.163 279.9)
-
Step 900
900
#373582
oklch(37.8% 0.126 279.7)
-
Step 950
950
#20204C
oklch(27.1% 0.079 279.7)
#665EF0 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) | #0079F5 | 0.087 |
| Deuteranopia (no green cones) | #006DED | 0.080 |
| Tritanopia (no blue cones) | #08829E | 0.183 |
| Achromatopsia (no color) | #737373 | 0.213 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #665EF0
#665EF0
oklch(57.3% 0.212 279.8)
- #897900
#897900
oklch(57.3% 0.119 100.1)
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 #665EF0, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Medium Slate Blue #7B68EE ΔE 0.041
- Neon Blue #4361EE ΔE 0.044
- Dark Periwinkle #665FD1 ΔE 0.047
- Light Indigo #6D5ACF ΔE 0.052
- Warm Blue #4B57DB ΔE 0.053
- Slate Blue #6A5ACD ΔE 0.054
- Royal Blue #4169E1 ΔE 0.054
- Purpley #8756E4 ΔE 0.056
Use #665EF0 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.