#378FDB
Closest named color: Dark Sky Blue (#448EE4). oklch(63.3% 0.141 248.4), rgb(55, 143, 219).
Aa
Black text reads best on this color (6.11:1).
About this color
#378FDB is a medium-light, vivid blue. In OKLCH its lightness is 63%, its chroma 0.141 and its hue 248°. Its hue sits on the cool side of the wheel. The nearest named color is Dark Sky Blue (#448EE4), ΔE 0.018 away. Black text reads best on it, at 6.11:1.
| Hue family | Blues |
| Lightness | medium-light (63%) |
| Chroma | vivid (0.141) |
| Temperature | cool |
| Nearest name | Dark Sky Blue (#448EE4) |
| Black text | 6.11:1 |
| White text | 3.43:1 |
Values
| HEX | #378FDB |
| RGB | rgb(55, 143, 219) |
| HSL | hsl(208, 69%, 54%) |
| OKLCH | oklch(63.3% 0.141 248.4) |
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 #378FDB | 3.43:1 | AA large text | Lc -67.0 | Content text, not long reading |
| Black text on #378FDB | 6.11:1 | AA | Lc 42.6 | Non-text elements, placeholder text |
| #378FDB text on white | 3.43:1 | AA large text | Lc 61.5 | Content text, not long reading |
| #378FDB text on black | 6.11:1 | AA | Lc -40.2 | 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
#9EC5EC
oklch(80.9% 0.069 248.7)
-
Step 400
400
#66A6E2
oklch(70.7% 0.11 248.2)
-
Step 500
500 (this color)
#378FDB
oklch(63.3% 0.141 248.4)
-
Step 600
600
#0077C6
oklch(55.6% 0.15 248.2)
-
Step 700
700
#0064A8
oklch(49.2% 0.133 248.3)
-
Step 800
800
#00518B
oklch(42.6% 0.117 248.8)
-
Step 900
900
#0E4470
oklch(37.7% 0.093 248.5)
-
Step 950
950
#0B2841
oklch(26.9% 0.058 248)
#378FDB 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) | #6C93DE | 0.051 |
| Deuteranopia (no green cones) | #5484DA | 0.034 |
| Tritanopia (no blue cones) | #00A1AB | 0.103 |
| Achromatopsia (no color) | #8A8A8A | 0.141 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #378FDB
#378FDB
oklch(63.3% 0.141 248.4)
- #C07700
#C07700
oklch(63.3% 0.139 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 #378FDB, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Dark Sky Blue #448EE4 ΔE 0.018
- Chefchaouen Blue #4895EF ΔE 0.036
- Water Blue #0E87CC ΔE 0.037
- Soft Blue #6488EA ΔE 0.050
- Cornflower Blue #6495ED ΔE 0.052
- Dodger Blue #1E90FF ΔE 0.054
- Cool Blue #4984B8 ΔE 0.055
- Faded Blue #658CBB ΔE 0.059
Use #378FDB 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.