#166DDF
Closest named color: Cerulean Blue (#056EEE). oklch(55.4% 0.191 258), rgb(22, 109, 223).
Aa
White text reads best on this color (4.89:1).
About this color
#166DDF is a medium-dark, vivid blue. In OKLCH its lightness is 55%, its chroma 0.191 and its hue 258°. Its hue sits on the cool side of the wheel. The nearest named color is Cerulean Blue (#056EEE), ΔE 0.023 away. White text reads best on it, at 4.89:1.
| Hue family | Blues |
| Lightness | medium-dark (55%) |
| Chroma | vivid (0.191) |
| Temperature | cool |
| Nearest name | Cerulean Blue (#056EEE) |
| Black text | 4.28:1 |
| White text | 4.89:1 |
Values
| HEX | #166DDF |
| RGB | rgb(22, 109, 223) |
| HSL | hsl(214, 82%, 48%) |
| OKLCH | oklch(55.4% 0.191 258) |
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 #166DDF | 4.89:1 | AA | Lc -78.7 | Fine for body text |
| Black text on #166DDF | 4.28:1 | AA large text | Lc 30.8 | Non-text elements, placeholder text |
| #166DDF text on white | 4.89:1 | AA | Lc 73.2 | Content text, not long reading |
| #166DDF text on black | 4.28:1 | AA large text | Lc -28.5 | 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
#F1F6FD
oklch(97.1% 0.011 256.7)
-
Step 100
100
#E0EBFB
oklch(93.7% 0.025 257.6)
-
Step 200
200
#C6DBF9
oklch(88.5% 0.047 257.3)
-
Step 300
300
#9EC3F8
oklch(80.9% 0.085 257.3)
-
Step 400
400
#68A1F5
oklch(70.6% 0.138 258)
-
Step 500
500
#3D87F1
oklch(63.1% 0.175 257.9)
-
Step 600
600 (this color)
#166DDF
oklch(55.4% 0.191 258)
-
Step 700
700
#065BC2
oklch(49.1% 0.177 257.9)
-
Step 800
800
#0C4B9D
oklch(42.7% 0.147 257.9)
-
Step 900
900
#14407D
oklch(37.8% 0.114 257.7)
-
Step 950
950
#0D2649
oklch(27.1% 0.072 257.4)
#166DDF 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) | #1B7AE3 | 0.034 |
| Deuteranopia (no green cones) | #0069DD | 0.013 |
| Tritanopia (no blue cones) | #00899B | 0.145 |
| Achromatopsia (no color) | #717171 | 0.191 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #166DDF
#166DDF
oklch(55.4% 0.191 258)
- #976900
#976900
oklch(55.4% 0.115 78.5)
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 #166DDF, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cerulean Blue #056EEE ΔE 0.023
- Royal Blue #4169E1 ΔE 0.029
- Azul #1D5DEC ΔE 0.043
- Neon Blue #4361EE ΔE 0.045
- Bright Blue #0165FC ΔE 0.049
- Clear Blue #247AFD ΔE 0.056
- Warm Blue #4B57DB ΔE 0.060
- Windows Blue #3778BF ΔE 0.065
Use #166DDF 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.