#378BC4
Closest named color: Cool Blue (#4984B8). oklch(61.2% 0.118 242.1), rgb(55, 139, 196).
Aa
Black text reads best on this color (5.65:1).
About this color
#378BC4 is a medium-dark, moderately saturated blue. In OKLCH its lightness is 61%, its chroma 0.118 and its hue 242°. Its hue sits on the cool side of the wheel. The nearest named color is Cool Blue (#4984B8), ΔE 0.025 away. Black text reads best on it, at 5.65:1.
| Hue family | Blues |
| Lightness | medium-dark (61%) |
| Chroma | moderately saturated (0.118) |
| Temperature | cool |
| Nearest name | Cool Blue (#4984B8) |
| Black text | 5.65:1 |
| White text | 3.71:1 |
Values
| HEX | #378BC4 |
| RGB | rgb(55, 139, 196) |
| HSL | hsl(204, 56%, 49%) |
| OKLCH | oklch(61.2% 0.118 242.1) |
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 #378BC4 | 3.71:1 | AA large text | Lc -69.9 | Content text, not long reading |
| Black text on #378BC4 | 5.65:1 | AA | Lc 39.7 | Non-text elements, placeholder text |
| #378BC4 text on white | 3.71:1 | AA large text | Lc 64.4 | Content text, not long reading |
| #378BC4 text on black | 5.65:1 | AA | Lc -37.3 | 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
#F1F6FA
oklch(97.1% 0.008 241.7)
-
Step 100
100
#E1ECF4
oklch(93.7% 0.016 239.1)
-
Step 200
200
#C8DCED
oklch(88.5% 0.032 243.7)
-
Step 300
300
#A1C6E3
oklch(80.9% 0.057 242)
-
Step 400
400
#6BA8D5
oklch(70.8% 0.092 241.7)
-
Step 500
500 (this color)
#378BC4
oklch(61.2% 0.118 242.1)
-
Step 600
600
#0F7AB7
oklch(55.6% 0.128 242.2)
-
Step 700
700
#00679D
oklch(49.2% 0.117 242)
-
Step 800
800
#065480
oklch(42.7% 0.099 242.1)
-
Step 900
900
#134667
oklch(37.8% 0.077 241.9)
-
Step 950
950
#0E293C
oklch(27% 0.048 242.2)
#378BC4 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) | #718CC7 | 0.058 |
| Deuteranopia (no green cones) | #5D7FC3 | 0.044 |
| Tritanopia (no blue cones) | #00999F | 0.082 |
| Achromatopsia (no color) | #848484 | 0.118 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #378BC4
#378BC4
oklch(61.2% 0.118 242.1)
- #B5722E
#B5722E
oklch(61.2% 0.118 62.4)
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 #378BC4, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cool Blue #4984B8 ΔE 0.025
- Water Blue #0E87CC ΔE 0.026
- Steel Blue #4682B4 ΔE 0.031
- Blue NCS #118AB2 ΔE 0.035
- Off Blue #5684AE ΔE 0.040
- Dusty Blue #5A86AD ΔE 0.042
- Faded Blue #658CBB ΔE 0.044
- Dark Sky Blue #448EE4 ΔE 0.050
Use #378BC4 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.