#1666B4
Closest named color: Mid Blue (#276AB3). oklch(50.7% 0.143 252.8), rgb(22, 102, 180).
Aa
White text reads best on this color (5.84:1).
About this color
#1666B4 is a medium-dark, vivid blue. In OKLCH its lightness is 51%, its chroma 0.143 and its hue 253°. Its hue sits on the cool side of the wheel. The nearest named color is Mid Blue (#276AB3), ΔE 0.016 away. White text reads best on it, at 5.84:1.
| Hue family | Blues |
| Lightness | medium-dark (51%) |
| Chroma | vivid (0.143) |
| Temperature | cool |
| Nearest name | Mid Blue (#276AB3) |
| Black text | 3.59:1 |
| White text | 5.84:1 |
Values
| HEX | #1666B4 |
| RGB | rgb(22, 102, 180) |
| HSL | hsl(210, 78%, 40%) |
| OKLCH | oklch(50.7% 0.143 252.8) |
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 #1666B4 | 5.84:1 | AA | Lc -84.0 | Fine for body text |
| Black text on #1666B4 | 3.59:1 | AA large text | Lc 25.4 | Dividers and decoration only |
| #1666B4 text on white | 5.84:1 | AA | Lc 78.7 | Fine for body text |
| #1666B4 text on black | 3.59:1 | AA large text | Lc -23.1 | 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
#F1F6FC
oklch(97.1% 0.01 252.8)
-
Step 100
100
#E1EBF7
oklch(93.6% 0.019 252.9)
-
Step 200
200
#C8DBF3
oklch(88.5% 0.039 254.3)
-
Step 300
300
#A1C4ED
oklch(80.9% 0.069 252.7)
-
Step 400
400
#6DA4E4
oklch(70.7% 0.111 253)
-
Step 500
500
#438CDC
oklch(63.1% 0.141 252.8)
-
Step 600
600
#1E74CA
oklch(55.6% 0.154 252.9)
-
Step 700
700 (this color)
#1666B4
oklch(50.7% 0.143 252.8)
-
Step 800
800
#11508D
oklch(42.8% 0.118 252.4)
-
Step 900
900
#174371
oklch(37.8% 0.092 252.4)
-
Step 950
950
#0F2742
oklch(26.9% 0.059 253.1)
#1666B4 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) | #3E6CB7 | 0.036 |
| Deuteranopia (no green cones) | #1E5FB2 | 0.019 |
| Tritanopia (no blue cones) | #007984 | 0.107 |
| Achromatopsia (no color) | #656565 | 0.143 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #1666B4
#1666B4
oklch(50.7% 0.143 252.8)
- #8A5A00
#8A5A00
oklch(50.8% 0.108 73.3)
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 #1666B4, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Mid Blue #276AB3 ΔE 0.016
- French Blue #436BAD ΔE 0.040
- Peacock Blue #016795 ΔE 0.052
- Flat Blue #3C73A8 ΔE 0.055
- Ocean Blue #03719C ΔE 0.055
- Muted Blue #3B719F ΔE 0.058
- Nice Blue #107AB0 ΔE 0.059
- Windows Blue #3778BF ΔE 0.059
Use #1666B4 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.