#1B3F73
Closest named color: Twilight Blue (#0A437A). oklch(37.1% 0.099 257.9), rgb(27, 63, 115).
Aa
White text reads best on this color (10.47:1).
About this color
#1B3F73 is a dark, moderately saturated blue. In OKLCH its lightness is 37%, its chroma 0.099 and its hue 258°. Its hue sits on the cool side of the wheel. The nearest named color is Twilight Blue (#0A437A), ΔE 0.017 away. White text reads best on it, at 10.47:1.
| Hue family | Blues |
| Lightness | dark (37%) |
| Chroma | moderately saturated (0.099) |
| Temperature | cool |
| Nearest name | Twilight Blue (#0A437A) |
| Black text | 2.00:1 |
| White text | 10.47:1 |
Values
| HEX | #1B3F73 |
| RGB | rgb(27, 63, 115) |
| HSL | hsl(215, 62%, 28%) |
| OKLCH | oklch(37.1% 0.099 257.9) |
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 #1B3F73 | 10.47:1 | AAA | Lc -98.0 | Preferred for body text |
| Black text on #1B3F73 | 2.00:1 | Fails | Lc 9.9 | Not readable |
| #1B3F73 text on white | 10.47:1 | AAA | Lc 94.0 | Preferred for body text |
| #1B3F73 text on black | 2.00:1 | Fails | Lc -8.5 | 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
#F1F6FC
oklch(97.1% 0.01 252.8)
-
Step 100
100
#E1EBF9
oklch(93.7% 0.022 256.7)
-
Step 200
200
#C9DBF5
oklch(88.6% 0.041 257.5)
-
Step 300
300
#A3C3F1
oklch(81% 0.074 257.4)
-
Step 400
400
#71A2EA
oklch(70.7% 0.119 257.9)
-
Step 500
500
#4B89E3
oklch(63.2% 0.15 257.8)
-
Step 600
600
#2C70D1
oklch(55.5% 0.165 258)
-
Step 700
700
#1F5EB5
oklch(49.2% 0.152 257.8)
-
Step 800
800
#1C4D93
oklch(42.8% 0.127 258)
-
Step 900
900 (this color)
#1B3F73
oklch(37.1% 0.099 257.9)
-
Step 950
950
#122644
oklch(26.9% 0.062 258.3)
#1B3F73 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) | #254475 | 0.020 |
| Deuteranopia (no green cones) | #153C72 | 0.011 |
| Tritanopia (no blue cones) | #004B53 | 0.077 |
| Achromatopsia (no color) | #3F3F3F | 0.099 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #1B3F73
#1B3F73
oklch(37.1% 0.099 257.9)
- #563A00
#563A00
oklch(37.1% 0.077 78.3)
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 #1B3F73, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Twilight Blue #0A437A ΔE 0.017
- Marine Blue #01386A ΔE 0.033
- Cobalt #1E488F ΔE 0.052
- Prussian Blue #1D3557 ΔE 0.053
- Dark Grey Blue #29465B ΔE 0.053
- Light Navy #155084 ΔE 0.054
- Deep Sea Blue #015482 ΔE 0.063
- Marine #042E60 ΔE 0.064
Use #1B3F73 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.