#378DDB
Closest named color: Dark Sky Blue (#448EE4). oklch(62.9% 0.143 249.4), rgb(55, 141, 219).
Aa
Black text reads best on this color (5.99:1).
About this color
#378DDB is a medium-light, vivid blue. In OKLCH its lightness is 63%, its chroma 0.143 and its hue 249°. Its hue sits on the cool side of the wheel. The nearest named color is Dark Sky Blue (#448EE4), ΔE 0.017 away. Black text reads best on it, at 5.99:1.
| Hue family | Blues |
| Lightness | medium-light (63%) |
| Chroma | vivid (0.143) |
| Temperature | cool |
| Nearest name | Dark Sky Blue (#448EE4) |
| Black text | 5.99:1 |
| White text | 3.50:1 |
Values
| HEX | #378DDB |
| RGB | rgb(55, 141, 219) |
| HSL | hsl(209, 69%, 54%) |
| OKLCH | oklch(62.9% 0.143 249.4) |
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 #378DDB | 3.50:1 | AA large text | Lc -67.7 | Content text, not long reading |
| Black text on #378DDB | 5.99:1 | AA | Lc 41.8 | Non-text elements, placeholder text |
| #378DDB text on white | 3.50:1 | AA large text | Lc 62.2 | Content text, not long reading |
| #378DDB text on black | 5.99:1 | AA | Lc -39.5 | Non-text elements, placeholder text |
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 500.
-
Step 50
50
#F1F6FC
oklch(97.1% 0.01 252.8)
-
Step 100
100
#E0EBF7
oklch(93.5% 0.02 250.4)
-
Step 200
200
#C6DCF2
oklch(88.5% 0.038 248.3)
-
Step 300
300
#9EC5ED
oklch(80.9% 0.071 249.4)
-
Step 400
400
#67A6E4
oklch(70.8% 0.112 249.3)
-
Step 500
500 (this color)
#378DDB
oklch(62.9% 0.143 249.4)
-
Step 600
600
#0076C9
oklch(55.6% 0.155 249.4)
-
Step 700
700
#0063AA
oklch(49.1% 0.137 249.4)
-
Step 800
800
#00518D
oklch(42.7% 0.12 249.5)
-
Step 900
900
#0F4471
oklch(37.8% 0.094 249.2)
-
Step 950
950
#0C2842
oklch(27.1% 0.059 249.5)
#378DDB 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) | #6991DE | 0.048 |
| Deuteranopia (no green cones) | #5182D9 | 0.033 |
| Tritanopia (no blue cones) | #00A0AA | 0.106 |
| Achromatopsia (no color) | #898989 | 0.143 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #378DDB
#378DDB
oklch(62.9% 0.143 249.4)
- #BD7700
#BD7700
oklch(62.9% 0.137 69.2)
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 #378DDB, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Dark Sky Blue #448EE4 ΔE 0.017
- Water Blue #0E87CC ΔE 0.035
- Chefchaouen Blue #4895EF ΔE 0.038
- Soft Blue #6488EA ΔE 0.049
- Dodger Blue #1E90FF ΔE 0.053
- Cool Blue #4984B8 ΔE 0.054
- Cornflower Blue #6495ED ΔE 0.055
- Faded Blue #658CBB ΔE 0.060
Use #378DDB 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.