#4378AA
Closest named color: Flat Blue (#3C73A8). oklch(55.8% 0.097 248.6), rgb(67, 120, 170).
Aa
White text reads best on this color (4.66:1).
About this color
#4378AA is a medium-dark, moderately saturated blue. In OKLCH its lightness is 56%, its chroma 0.097 and its hue 249°. Its hue sits on the cool side of the wheel. The nearest named color is Flat Blue (#3C73A8), ΔE 0.017 away. White text reads best on it, at 4.66:1.
| Hue family | Blues |
| Lightness | medium-dark (56%) |
| Chroma | moderately saturated (0.097) |
| Temperature | cool |
| Nearest name | Flat Blue (#3C73A8) |
| Black text | 4.50:1 |
| White text | 4.66:1 |
Values
| HEX | #4378AA |
| RGB | rgb(67, 120, 170) |
| HSL | hsl(209, 43%, 46%) |
| OKLCH | oklch(55.8% 0.097 248.6) |
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 #4378AA | 4.66:1 | AA | Lc -77.6 | Fine for body text |
| Black text on #4378AA | 4.50:1 | AA | Lc 31.9 | Non-text elements, placeholder text |
| #4378AA text on white | 4.66:1 | AA | Lc 72.2 | Content text, not long reading |
| #4378AA text on black | 4.50:1 | AA | Lc -29.5 | 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
#F2F6F9
oklch(97.1% 0.006 239.8)
-
Step 100
100
#E4EBF2
oklch(93.7% 0.012 248)
-
Step 200
200
#CDDBE9
oklch(88.5% 0.025 248.1)
-
Step 300
300
#ABC4DC
oklch(80.9% 0.044 247.3)
-
Step 400
400
#7FA5CB
oklch(70.8% 0.07 248.8)
-
Step 500
500
#5D8EBD
oklch(63.1% 0.089 248.4)
-
Step 600
600 (this color)
#4378AA
oklch(55.8% 0.097 248.6)
-
Step 700
700
#346491
oklch(49% 0.09 248.7)
-
Step 800
800
#2C5276
oklch(42.8% 0.074 248.8)
-
Step 900
900
#28445F
oklch(37.7% 0.058 248.7)
-
Step 950
950
#182838
oklch(27.1% 0.037 249.3)
#4378AA 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) | #637AAC | 0.038 |
| Deuteranopia (no green cones) | #5570A9 | 0.027 |
| Tritanopia (no blue cones) | #00848A | 0.078 |
| Achromatopsia (no color) | #747474 | 0.097 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #4378AA
#4378AA
oklch(55.8% 0.097 248.6)
- #99682E
#99682E
oklch(55.8% 0.097 67.9)
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 #4378AA, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Flat Blue #3C73A8 ΔE 0.017
- Dull Blue #49759C ΔE 0.022
- Cerulean #457B9D ΔE 0.025
- Muted Blue #3B719F ΔE 0.026
- Stormy Blue #507B9C ΔE 0.029
- Nice Blue #107AB0 ΔE 0.030
- Steel Blue #4682B4 ΔE 0.030
- Windows Blue #3778BF ΔE 0.034
Use #4378AA 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.