#166AEF
Closest named color: Cerulean Blue (#056EEE). oklch(56% 0.215 260.2), rgb(22, 106, 239).
Aa
White text reads best on this color (4.83:1).
About this color
#166AEF is a medium-dark, vivid blue. In OKLCH its lightness is 56%, its chroma 0.215 and its hue 260°. Its hue sits on the cool side of the wheel. The nearest named color is Cerulean Blue (#056EEE), ΔE 0.010 away. White text reads best on it, at 4.83:1.
| Hue family | Blues |
| Lightness | medium-dark (56%) |
| Chroma | vivid (0.215) |
| Temperature | cool |
| Nearest name | Cerulean Blue (#056EEE) |
| Black text | 4.34:1 |
| White text | 4.83:1 |
Values
| HEX | #166AEF |
| RGB | rgb(22, 106, 239) |
| HSL | hsl(217, 87%, 51%) |
| OKLCH | oklch(56% 0.215 260.2) |
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 #166AEF | 4.83:1 | AA | Lc -78.2 | Fine for body text |
| Black text on #166AEF | 4.34:1 | AA large text | Lc 31.3 | Non-text elements, placeholder text |
| #166AEF text on white | 4.83:1 | AA | Lc 72.7 | Content text, not long reading |
| #166AEF text on black | 4.34:1 | AA large text | Lc -29.0 | 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
#F0F6FE
oklch(97.1% 0.012 255.5)
-
Step 100
100
#DFEBFD
oklch(93.6% 0.028 258.4)
-
Step 200
200
#C5DAFD
oklch(88.4% 0.054 260.6)
-
Step 300
300
#9DC2FF
oklch(81% 0.096 260.2)
-
Step 400
400
#669FFF
oklch(70.7% 0.154 260.3)
-
Step 500
500
#3A83FE
oklch(63% 0.197 260.2)
-
Step 600
600 (this color)
#166AEF
oklch(56% 0.215 260.2)
-
Step 700
700
#0456CF
oklch(49.1% 0.2 260.3)
-
Step 800
800
#0A47A7
oklch(42.6% 0.165 260.3)
-
Step 900
900
#123D84
oklch(37.6% 0.129 260.1)
-
Step 950
950
#0C244D
oklch(26.8% 0.082 260.4)
#166AEF 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) | #007CF4 | 0.044 |
| Deuteranopia (no green cones) | #0069EC | 0.008 |
| Tritanopia (no blue cones) | #008CA2 | 0.164 |
| Achromatopsia (no color) | #727272 | 0.215 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #166AEF
#166AEF
oklch(56% 0.215 260.2)
- #976B00
#976B00
oklch(55.9% 0.116 80.2)
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 #166AEF, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cerulean Blue #056EEE ΔE 0.010
- Bright Blue #0165FC ΔE 0.024
- Azul #1D5DEC ΔE 0.030
- Neon Blue #4361EE ΔE 0.033
- Royal Blue #4169E1 ΔE 0.034
- Clear Blue #247AFD ΔE 0.046
- Electric Blue #0652FF ΔE 0.058
- Warm Blue #4B57DB ΔE 0.060
Use #166AEF 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.