#17378F
Closest named color: Cobalt (#1E488F). oklch(37.5% 0.151 264.7), rgb(23, 55, 143).
Aa
White text reads best on this color (10.60:1).
About this color
#17378F is a dark, vivid blue. In OKLCH its lightness is 37%, its chroma 0.151 and its hue 265°. Its hue sits on the cool side of the wheel. The nearest named color is Cobalt (#1E488F), ΔE 0.047 away. White text reads best on it, at 10.60:1.
| Hue family | Blues |
| Lightness | dark (37%) |
| Chroma | vivid (0.151) |
| Temperature | cool |
| Nearest name | Cobalt (#1E488F) |
| Black text | 1.97:1 |
| White text | 10.60:1 |
Values
| HEX | #17378F |
| RGB | rgb(23, 55, 143) |
| HSL | hsl(224, 72%, 33%) |
| OKLCH | oklch(37.5% 0.151 264.7) |
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 #17378F | 10.60:1 | AAA | Lc -98.0 | Preferred for body text |
| Black text on #17378F | 1.97:1 | Fails | Lc 9.9 | Not readable |
| #17378F text on white | 10.60:1 | AAA | Lc 94.0 | Preferred for body text |
| #17378F text on black | 1.97:1 | Fails | Lc -8.6 | Not readable |
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 900.
-
Step 50
50
#F1F6FF
oklch(97.2% 0.013 262.4)
-
Step 100
100
#E0EAFF
oklch(93.6% 0.03 265.3)
-
Step 200
200
#C7D9FF
oklch(88.4% 0.056 265.2)
-
Step 300
300
#A2C0FF
oklch(80.9% 0.096 264.7)
-
Step 400
400
#719DFF
oklch(70.8% 0.152 264.6)
-
Step 500
500
#4C80FF
oklch(63.2% 0.197 264.6)
-
Step 600
600
#285FFF
oklch(55.7% 0.244 264.7)
-
Step 700
700
#1A4BE2
oklch(49.2% 0.233 264.6)
-
Step 800
800
#173FB6
oklch(42.7% 0.193 264.7)
-
Step 900
900 (this color)
#17378F
oklch(37.5% 0.151 264.7)
-
Step 950
950
#0E2254
oklch(27% 0.095 264.4)
#17378F 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) | #004492 | 0.033 |
| Deuteranopia (no green cones) | #00398D | 0.013 |
| Tritanopia (no blue cones) | #004E5D | 0.118 |
| Achromatopsia (no color) | #3F3F3F | 0.151 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #17378F
#17378F
oklch(37.5% 0.151 264.7)
- #543D00
#543D00
oklch(37.5% 0.077 84.5)
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 #17378F, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cobalt #1E488F ΔE 0.047
- Sapphire #2138AB ΔE 0.048
- Twilight Blue #0A437A ΔE 0.050
- Marine Blue #01386A ΔE 0.066
- Royal #0C1793 ΔE 0.067
- Dark Slate Blue #483D8B ΔE 0.069
- Blueberry #464196 ΔE 0.070
- Light Navy #155084 ΔE 0.074
Use #17378F 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.