#307B9D
Closest named color: Cerulean (#457B9D). oklch(55.1% 0.09 231.3), rgb(48, 123, 157).
Aa
White text reads best on this color (4.72:1).
About this color
#307B9D is a medium-dark, moderately saturated blue. In OKLCH its lightness is 55%, its chroma 0.090 and its hue 231°. Its hue sits on the cool side of the wheel. The nearest named color is Cerulean (#457B9D), ΔE 0.017 away. White text reads best on it, at 4.72:1.
| Hue family | Blues |
| Lightness | medium-dark (55%) |
| Chroma | moderately saturated (0.090) |
| Temperature | cool |
| Nearest name | Cerulean (#457B9D) |
| Black text | 4.44:1 |
| White text | 4.72:1 |
Values
| HEX | #307B9D |
| RGB | rgb(48, 123, 157) |
| HSL | hsl(199, 53%, 40%) |
| OKLCH | oklch(55.1% 0.09 231.3) |
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 #307B9D | 4.72:1 | AA | Lc -78.0 | Fine for body text |
| Black text on #307B9D | 4.44:1 | AA large text | Lc 31.5 | Non-text elements, placeholder text |
| #307B9D text on white | 4.72:1 | AA | Lc 72.5 | Content text, not long reading |
| #307B9D text on black | 4.44:1 | AA large text | Lc -29.1 | Dividers and decoration only |
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 600.
-
Step 50
50
#F2F6F8
oklch(97.1% 0.005 228.8)
-
Step 100
100
#E2EBF0
oklch(93.5% 0.012 231.7)
-
Step 200
200
#CBDCE6
oklch(88.5% 0.023 233.4)
-
Step 300
300
#A7C6D6
oklch(80.9% 0.04 230.3)
-
Step 400
400
#77A8C2
oklch(70.6% 0.065 232)
-
Step 500
500
#5193B3
oklch(63.2% 0.083 231.1)
-
Step 600
600 (this color)
#307B9D
oklch(55.1% 0.09 231.3)
-
Step 700
700
#236988
oklch(49.2% 0.084 231.4)
-
Step 800
800
#1F556E
oklch(42.5% 0.07 231.8)
-
Step 900
900
#204759
oklch(37.8% 0.054 230.4)
-
Step 950
950
#142934
oklch(26.9% 0.034 232.8)
#307B9D 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) | #6A799F | 0.061 |
| Deuteranopia (no green cones) | #5B6F9D | 0.052 |
| Tritanopia (no blue cones) | #008486 | 0.055 |
| Achromatopsia (no color) | #737373 | 0.090 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #307B9D
#307B9D
oklch(55.1% 0.09 231.3)
- #9C623F
#9C623F
oklch(55.2% 0.09 51.1)
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 #307B9D, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cerulean #457B9D ΔE 0.017
- Dull Blue #49759C ΔE 0.025
- Ocean #017B92 ΔE 0.028
- Stormy Blue #507B9C ΔE 0.029
- Muted Blue #3B719F ΔE 0.031
- Sea Blue #047495 ΔE 0.033
- Nice Blue #107AB0 ΔE 0.033
- Flat Blue #3C73A8 ΔE 0.034
Use #307B9D 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.