#378BBF
Closest named color: Cool Blue (#4984B8). oklch(60.9% 0.112 239.7), rgb(55, 139, 191).
Aa
Black text reads best on this color (5.60:1).
About this color
#378BBF is a medium-dark, moderately saturated blue. In OKLCH its lightness is 61%, its chroma 0.112 and its hue 240°. Its hue sits on the cool side of the wheel. The nearest named color is Cool Blue (#4984B8), ΔE 0.022 away. Black text reads best on it, at 5.60:1.
| Hue family | Blues |
| Lightness | medium-dark (61%) |
| Chroma | moderately saturated (0.112) |
| Temperature | cool |
| Nearest name | Cool Blue (#4984B8) |
| Black text | 5.60:1 |
| White text | 3.74:1 |
Values
| HEX | #378BBF |
| RGB | rgb(55, 139, 191) |
| HSL | hsl(203, 55%, 48%) |
| OKLCH | oklch(60.9% 0.112 239.7) |
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 #378BBF | 3.74:1 | AA large text | Lc -70.2 | Content text, not long reading |
| Black text on #378BBF | 5.60:1 | AA | Lc 39.4 | Non-text elements, placeholder text |
| #378BBF text on white | 3.74:1 | AA large text | Lc 64.7 | Content text, not long reading |
| #378BBF text on black | 5.60:1 | AA | Lc -37.0 | 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
#C8DCEC
oklch(88.4% 0.031 242)
-
Step 300
300
#A1C6E1
oklch(80.9% 0.055 240)
-
Step 400
400
#6BA8D2
oklch(70.6% 0.088 239.8)
-
Step 500
500 (this color)
#378BBF
oklch(60.9% 0.112 239.7)
-
Step 600
600
#117BB3
oklch(55.6% 0.122 239.9)
-
Step 700
700
#006799
oklch(49% 0.112 240)
-
Step 800
800
#07557D
oklch(42.8% 0.094 239.4)
-
Step 900
900
#144664
oklch(37.7% 0.073 239.6)
-
Step 950
950
#0E293B
oklch(27% 0.047 240.8)
#378BBF 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) | #738BC1 | 0.060 |
| Deuteranopia (no green cones) | #607EBE | 0.048 |
| Tritanopia (no blue cones) | #00989D | 0.076 |
| Achromatopsia (no color) | #848484 | 0.112 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #378BBF
#378BBF
oklch(60.9% 0.112 239.7)
- #B47136
#B47136
oklch(61% 0.113 59.4)
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 #378BBF, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Cool Blue #4984B8 ΔE 0.022
- Steel Blue #4682B4 ΔE 0.027
- Blue NCS #118AB2 ΔE 0.028
- Water Blue #0E87CC ΔE 0.031
- Off Blue #5684AE ΔE 0.035
- Dusty Blue #5A86AD ΔE 0.037
- Faded Blue #658CBB ΔE 0.043
- Windows Blue #3778BF ΔE 0.055
Use #378BBF 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.