#166CE5
Closest named color: Cerulean Blue (#056EEE). oklch(55.6% 0.2 258.9), rgb(22, 108, 229).
Aa
White text reads best on this color (4.87:1).
About this color
#166CE5 is a medium-dark, vivid blue. In OKLCH its lightness is 56%, its chroma 0.200 and its hue 259°. Its hue sits on the cool side of the wheel. The nearest named color is Cerulean Blue (#056EEE), ΔE 0.014 away. White text reads best on it, at 4.87:1.
| Hue family | Blues |
| Lightness | medium-dark (56%) |
| Chroma | vivid (0.200) |
| Temperature | cool |
| Nearest name | Cerulean Blue (#056EEE) |
| Black text | 4.31:1 |
| White text | 4.87:1 |
Values
| HEX | #166CE5 |
| RGB | rgb(22, 108, 229) |
| HSL | hsl(215, 82%, 49%) |
| OKLCH | oklch(55.6% 0.2 258.9) |
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 #166CE5 | 4.87:1 | AA | Lc -78.5 | Fine for body text |
| Black text on #166CE5 | 4.31:1 | AA large text | Lc 31.0 | Non-text elements, placeholder text |
| #166CE5 text on white | 4.87:1 | AA | Lc 73.0 | Content text, not long reading |
| #166CE5 text on black | 4.31:1 | AA large text | Lc -28.7 | 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
#F1F6FE
oklch(97.2% 0.012 259.8)
-
Step 100
100
#E0EBFC
oklch(93.7% 0.026 259)
-
Step 200
200
#C6DBFB
oklch(88.6% 0.05 258.7)
-
Step 300
300
#9EC2FB
oklch(80.9% 0.09 259.4)
-
Step 400
400
#67A0F9
oklch(70.6% 0.144 259)
-
Step 500
500
#3C86F6
oklch(63.2% 0.183 258.7)
-
Step 600
600 (this color)
#166CE5
oklch(55.6% 0.2 258.9)
-
Step 700
700
#0559C7
oklch(49.1% 0.186 258.9)
-
Step 800
800
#0B4AA1
oklch(42.8% 0.153 258.7)
-
Step 900
900
#133F80
oklch(37.8% 0.12 258.7)
-
Step 950
950
#0D254B
oklch(27% 0.077 259.3)
#166CE5 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) | #007BE9 | 0.038 |
| Deuteranopia (no green cones) | #0069E3 | 0.011 |
| Tritanopia (no blue cones) | #008A9E | 0.151 |
| Achromatopsia (no color) | #717171 | 0.200 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #166CE5
#166CE5
oklch(55.6% 0.2 258.9)
- #976A00
#976A00
oklch(55.7% 0.116 79.3)
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 #166CE5, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cerulean Blue #056EEE ΔE 0.014
- Royal Blue #4169E1 ΔE 0.028
- Azul #1D5DEC ΔE 0.037
- Neon Blue #4361EE ΔE 0.039
- Bright Blue #0165FC ΔE 0.039
- Clear Blue #247AFD ΔE 0.051
- Warm Blue #4B57DB ΔE 0.058
- Electric Blue #0652FF ΔE 0.071
Use #166CE5 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.