#1F3F71
Closest named color: Twilight Blue (#0A437A). oklch(37.1% 0.094 259), rgb(31, 63, 113).
Aa
White text reads best on this color (10.45:1).
About this color
#1F3F71 is a dark, moderately saturated blue. In OKLCH its lightness is 37%, its chroma 0.094 and its hue 259°. Its hue sits on the cool side of the wheel. The nearest named color is Twilight Blue (#0A437A), ΔE 0.021 away. White text reads best on it, at 10.45:1.
| Hue family | Blues |
| Lightness | dark (37%) |
| Chroma | moderately saturated (0.094) |
| Temperature | cool |
| Nearest name | Twilight Blue (#0A437A) |
| Black text | 2.00:1 |
| White text | 10.45:1 |
Values
| HEX | #1F3F71 |
| RGB | rgb(31, 63, 113) |
| HSL | hsl(217, 57%, 28%) |
| OKLCH | oklch(37.1% 0.094 259) |
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 #1F3F71 | 10.45:1 | AAA | Lc -98.0 | Preferred for body text |
| Black text on #1F3F71 | 2.00:1 | Fails | Lc 9.9 | Not readable |
| #1F3F71 text on white | 10.45:1 | AAA | Lc 94.0 | Preferred for body text |
| #1F3F71 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
#F2F6FC
oklch(97.2% 0.009 258.3)
-
Step 100
100
#E2EBF8
oklch(93.7% 0.02 257.5)
-
Step 200
200
#CADAF4
oklch(88.4% 0.04 260.1)
-
Step 300
300
#A6C2EF
oklch(80.9% 0.071 259.8)
-
Step 400
400
#75A1E7
oklch(70.6% 0.114 259.4)
-
Step 500
500
#5188DF
oklch(63% 0.144 259.2)
-
Step 600
600
#3570CD
oklch(55.5% 0.157 259.3)
-
Step 700
700
#275EB2
oklch(49.2% 0.146 258.9)
-
Step 800
800
#224D90
oklch(42.8% 0.121 259.1)
-
Step 900
900 (this color)
#1F3F71
oklch(37.1% 0.094 259)
-
Step 950
950
#142643
oklch(27% 0.059 259.5)
#1F3F71 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) | #274473 | 0.019 |
| Deuteranopia (no green cones) | #1A3C70 | 0.011 |
| Tritanopia (no blue cones) | #004B52 | 0.076 |
| Achromatopsia (no color) | #3F3F3F | 0.094 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #1F3F71
#1F3F71
oklch(37.1% 0.094 259)
- #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 #1F3F71, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Twilight Blue #0A437A ΔE 0.021
- Marine Blue #01386A ΔE 0.035
- Dark Grey Blue #29465B ΔE 0.050
- Prussian Blue #1D3557 ΔE 0.051
- Cobalt #1E488F ΔE 0.054
- Light Navy #155084 ΔE 0.055
- Charcoal #264653 ΔE 0.062
- Dark Blue Grey #1F3B4D ΔE 0.062
Use #1F3F71 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.