#303666
Closest named color: Prussian Blue (#1D3557). oklch(35.3% 0.083 275.9), rgb(48, 54, 102).
Aa
White text reads best on this color (11.38:1).
About this color
#303666 is a dark, moderately saturated blue. In OKLCH its lightness is 35%, its chroma 0.083 and its hue 276°. Its hue sits on the cool side of the wheel. The nearest named color is Prussian Blue (#1D3557), ΔE 0.038 away. White text reads best on it, at 11.38:1.
| Hue family | Blues |
| Lightness | dark (35%) |
| Chroma | moderately saturated (0.083) |
| Temperature | cool |
| Nearest name | Prussian Blue (#1D3557) |
| Black text | 1.84:1 |
| White text | 11.38:1 |
Values
| HEX | #303666 |
| RGB | rgb(48, 54, 102) |
| HSL | hsl(233, 36%, 29%) |
| OKLCH | oklch(35.3% 0.083 275.9) |
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 #303666 | 11.38:1 | AAA | Lc -99.9 | Preferred for body text |
| Black text on #303666 | 1.84:1 | Fails | Lc 7.8 | Not readable |
| #303666 text on white | 11.38:1 | AAA | Lc 96.1 | Preferred for body text |
| #303666 text on black | 1.84:1 | Fails | Lc 0.0 | 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
#F4F5FB
oklch(97.1% 0.008 278.6)
-
Step 100
100
#E6E9F6
oklch(93.6% 0.018 275.6)
-
Step 200
200
#D2D8F1
oklch(88.5% 0.035 274.9)
-
Step 300
300
#B5BEE9
oklch(80.9% 0.062 275.7)
-
Step 400
400
#8F9BDF
oklch(70.6% 0.101 275.8)
-
Step 500
500
#7581D6
oklch(63.1% 0.128 276)
-
Step 600
600
#5F69C3
oklch(55.6% 0.139 276.2)
-
Step 700
700
#4E57A8
oklch(49.1% 0.128 275.8)
-
Step 800
800
#404888
oklch(42.8% 0.105 275.6)
-
Step 900
900 (this color)
#303666
oklch(35.3% 0.083 275.9)
-
Step 950
950
#202440
oklch(27.1% 0.052 276.2)
#303666 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) | #223C68 | 0.023 |
| Deuteranopia (no green cones) | #1D3865 | 0.025 |
| Tritanopia (no blue cones) | #1A4049 | 0.073 |
| Achromatopsia (no color) | #3A3A3A | 0.083 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #303666
#303666
oklch(35.3% 0.083 275.9)
- #473B00
#473B00
oklch(35.4% 0.073 96.2)
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 #303666, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Prussian Blue #1D3557 ΔE 0.038
- Marine Blue #01386A ΔE 0.044
- Twilight Blue #0A437A ΔE 0.054
- Dark Blue Grey #1F3B4D ΔE 0.056
- Dark Grey Blue #29465B ΔE 0.058
- Marine #042E60 ΔE 0.058
- Space Cadet #2B2D42 ΔE 0.066
- Gunmetal #293241 ΔE 0.067
Use #303666 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.