#377DCB
Closest named color: Windows Blue (#3778BF). oklch(58.3% 0.139 253.4), rgb(55, 125, 203).
Aa
Black text reads best on this color (4.95:1).
About this color
#377DCB is a medium-dark, moderately saturated blue. In OKLCH its lightness is 58%, its chroma 0.139 and its hue 253°. Its hue sits on the cool side of the wheel. The nearest named color is Windows Blue (#3778BF), ΔE 0.021 away. Black text reads best on it, at 4.95:1.
| Hue family | Blues |
| Lightness | medium-dark (58%) |
| Chroma | moderately saturated (0.139) |
| Temperature | cool |
| Nearest name | Windows Blue (#3778BF) |
| Black text | 4.95:1 |
| White text | 4.23:1 |
Values
| HEX | #377DCB |
| RGB | rgb(55, 125, 203) |
| HSL | hsl(212, 59%, 51%) |
| OKLCH | oklch(58.3% 0.139 253.4) |
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 #377DCB | 4.23:1 | AA large text | Lc -74.4 | Content text, not long reading |
| Black text on #377DCB | 4.95:1 | AA | Lc 35.2 | Non-text elements, placeholder text |
| #377DCB text on white | 4.23:1 | AA large text | Lc 68.9 | Content text, not long reading |
| #377DCB text on black | 4.95:1 | AA | Lc -32.8 | 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 600.
-
Step 50
50
#F2F6FB
oklch(97.2% 0.008 253.9)
-
Step 100
100
#E2EBF6
oklch(93.7% 0.018 253.3)
-
Step 200
200
#CADBF0
oklch(88.5% 0.034 253.7)
-
Step 300
300
#A5C4E9
oklch(81% 0.062 253.1)
-
Step 400
400
#73A4DE
oklch(70.7% 0.1 253.3)
-
Step 500
500
#4D8CD5
oklch(63.1% 0.128 253.5)
-
Step 600
600 (this color)
#377DCB
oklch(58.3% 0.139 253.4)
-
Step 700
700
#2062A7
oklch(49.2% 0.128 252.9)
-
Step 800
800
#1D5088
oklch(42.8% 0.108 253.4)
-
Step 900
900
#1E436D
oklch(37.8% 0.084 253.4)
-
Step 950
950
#122740
oklch(26.9% 0.054 254)
#377DCB 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) | #5982CE | 0.037 |
| Deuteranopia (no green cones) | #4275C9 | 0.022 |
| Tritanopia (no blue cones) | #008F9A | 0.106 |
| Achromatopsia (no color) | #7B7B7B | 0.139 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #377DCB
#377DCB
oklch(58.3% 0.139 253.4)
- #A76E00
#A76E00
oklch(58.4% 0.124 73.4)
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 #377DCB, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Windows Blue #3778BF ΔE 0.021
- Water Blue #0E87CC ΔE 0.030
- Cool Blue #4984B8 ΔE 0.042
- Steel Blue #4682B4 ΔE 0.043
- Nice Blue #107AB0 ΔE 0.049
- Flat Blue #3C73A8 ΔE 0.056
- Dark Sky Blue #448EE4 ΔE 0.058
- Off Blue #5684AE ΔE 0.060
Use #377DCB 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.