#166CB5
Closest named color: Mid Blue (#276AB3). oklch(52.2% 0.138 250.1), rgb(22, 108, 181).
Aa
White text reads best on this color (5.45:1).
About this color
#166CB5 is a medium-dark, moderately saturated blue. In OKLCH its lightness is 52%, its chroma 0.138 and its hue 250°. Its hue sits on the cool side of the wheel. The nearest named color is Mid Blue (#276AB3), ΔE 0.009 away. White text reads best on it, at 5.45:1.
| Hue family | Blues |
| Lightness | medium-dark (52%) |
| Chroma | moderately saturated (0.138) |
| Temperature | cool |
| Nearest name | Mid Blue (#276AB3) |
| Black text | 3.84:1 |
| White text | 5.45:1 |
Values
| HEX | #166CB5 |
| RGB | rgb(22, 108, 181) |
| HSL | hsl(208, 78%, 40%) |
| OKLCH | oklch(52.2% 0.138 250.1) |
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 #166CB5 | 5.45:1 | AA | Lc -82.1 | Fine for body text |
| Black text on #166CB5 | 3.84:1 | AA large text | Lc 27.3 | Dividers and decoration only |
| #166CB5 text on white | 5.45:1 | AA | Lc 76.7 | Fine for body text |
| #166CB5 text on black | 3.84:1 | AA large text | Lc -25.0 | 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 700.
-
Step 50
50
#F1F6FB
oklch(97.1% 0.009 247.9)
-
Step 100
100
#E1EBF7
oklch(93.6% 0.019 252.9)
-
Step 200
200
#C7DCF1
oklch(88.5% 0.037 248.2)
-
Step 300
300
#A0C5EB
oklch(81% 0.067 249.3)
-
Step 400
400
#6BA5E1
oklch(70.6% 0.107 250.3)
-
Step 500
500
#408DD8
oklch(63% 0.136 250.4)
-
Step 600
600
#1776C6
oklch(55.6% 0.149 250.2)
-
Step 700
700 (this color)
#166CB5
oklch(52.2% 0.138 250.1)
-
Step 800
800
#0C518A
oklch(42.7% 0.114 249.9)
-
Step 900
900
#15436F
oklch(37.6% 0.09 250.8)
-
Step 950
950
#0E2841
oklch(27.1% 0.057 249.9)
#166CB5 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) | #4871B8 | 0.042 |
| Deuteranopia (no green cones) | #2D63B4 | 0.026 |
| Tritanopia (no blue cones) | #007E87 | 0.102 |
| Achromatopsia (no color) | #696969 | 0.138 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #166CB5
#166CB5
oklch(52.2% 0.138 250.1)
- #925C00
#925C00
oklch(52.2% 0.113 70.3)
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 #166CB5, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Mid Blue #276AB3 ΔE 0.009
- French Blue #436BAD ΔE 0.033
- Flat Blue #3C73A8 ΔE 0.041
- Nice Blue #107AB0 ΔE 0.043
- Windows Blue #3778BF ΔE 0.044
- Ocean Blue #03719C ΔE 0.046
- Muted Blue #3B719F ΔE 0.047
- Peacock Blue #016795 ΔE 0.053
Use #166CB5 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.