#1D378B
Closest named color: Twilight Blue (#0A437A). oklch(37.3% 0.143 266.3), rgb(29, 55, 139).
Aa
White text reads best on this color (10.65:1).
About this color
#1D378B is a dark, vivid blue. In OKLCH its lightness is 37%, its chroma 0.143 and its hue 266°. Its hue sits on the cool side of the wheel. The nearest named color is Twilight Blue (#0A437A), ΔE 0.046 away. White text reads best on it, at 10.65:1.
| Hue family | Blues |
| Lightness | dark (37%) |
| Chroma | vivid (0.143) |
| Temperature | cool |
| Nearest name | Twilight Blue (#0A437A) |
| Black text | 1.97:1 |
| White text | 10.65:1 |
Values
| HEX | #1D378B |
| RGB | rgb(29, 55, 139) |
| HSL | hsl(226, 65%, 33%) |
| OKLCH | oklch(37.3% 0.143 266.3) |
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 #1D378B | 10.65:1 | AAA | Lc -98.2 | Preferred for body text |
| Black text on #1D378B | 1.97:1 | Fails | Lc 9.8 | Not readable |
| #1D378B text on white | 10.65:1 | AAA | Lc 94.2 | Preferred for body text |
| #1D378B text on black | 1.97:1 | Fails | Lc -8.4 | 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
#F1F5FF
oklch(97% 0.014 268.5)
-
Step 100
100
#E0EAFF
oklch(93.6% 0.03 265.3)
-
Step 200
200
#C8D9FF
oklch(88.5% 0.056 266.2)
-
Step 300
300
#A4BFFF
oklch(80.8% 0.096 266.6)
-
Step 400
400
#749CFF
oklch(70.8% 0.152 266)
-
Step 500
500
#517FFF
oklch(63.2% 0.197 266)
-
Step 600
600
#325EFC
oklch(55.5% 0.239 266.2)
-
Step 700
700
#274CDC
oklch(49.1% 0.222 266.3)
-
Step 800
800
#2040B1
oklch(42.7% 0.183 266.1)
-
Step 900
900 (this color)
#1D378B
oklch(37.3% 0.143 266.3)
-
Step 950
950
#122252
oklch(27.1% 0.09 266.4)
#1D378B 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) | #00448E | 0.035 |
| Deuteranopia (no green cones) | #003989 | 0.018 |
| Tritanopia (no blue cones) | #004C5B | 0.112 |
| Achromatopsia (no color) | #3E3E3E | 0.144 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #1D378B
#1D378B
oklch(37.3% 0.143 266.3)
- #523D00
#523D00
oklch(37.3% 0.076 86.6)
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 #1D378B, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Twilight Blue #0A437A ΔE 0.046
- Cobalt #1E488F ΔE 0.046
- Sapphire #2138AB ΔE 0.053
- Marine Blue #01386A ΔE 0.061
- Dark Slate Blue #483D8B ΔE 0.064
- Blueberry #464196 ΔE 0.067
- Royal #0C1793 ΔE 0.070
- Light Navy #155084 ΔE 0.072
Use #1D378B 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.