#337ECC
Closest named color: Windows Blue (#3778BF). oklch(58.5% 0.141 252.2), rgb(51, 126, 204).
Aa
Black text reads best on this color (4.99:1).
About this color
#337ECC is a medium-dark, vivid blue. In OKLCH its lightness is 58%, its chroma 0.141 and its hue 252°. Its hue sits on the cool side of the wheel. The nearest named color is Windows Blue (#3778BF), ΔE 0.023 away. Black text reads best on it, at 4.99:1.
| Hue family | Blues |
| Lightness | medium-dark (58%) |
| Chroma | vivid (0.141) |
| Temperature | cool |
| Nearest name | Windows Blue (#3778BF) |
| Black text | 4.99:1 |
| White text | 4.20:1 |
Values
| HEX | #337ECC |
| RGB | rgb(51, 126, 204) |
| HSL | hsl(211, 60%, 50%) |
| OKLCH | oklch(58.5% 0.141 252.2) |
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 #337ECC | 4.20:1 | AA large text | Lc -74.1 | Content text, not long reading |
| Black text on #337ECC | 4.99:1 | AA | Lc 35.5 | Non-text elements, placeholder text |
| #337ECC text on white | 4.20:1 | AA large text | Lc 68.6 | Content text, not long reading |
| #337ECC text on black | 4.99:1 | AA | Lc -33.0 | 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 600.
-
Step 50
50
#F1F6FB
oklch(97.1% 0.009 247.9)
-
Step 100
100
#E1EBF6
oklch(93.6% 0.018 250.6)
-
Step 200
200
#C9DBF0
oklch(88.4% 0.035 252.3)
-
Step 300
300
#A4C4E9
oklch(80.9% 0.063 252.3)
-
Step 400
400
#71A4DE
oklch(70.6% 0.101 252.4)
-
Step 500
500
#4A8DD5
oklch(63.2% 0.129 252)
-
Step 600
600 (this color)
#337ECC
oklch(58.5% 0.141 252.2)
-
Step 700
700
#1B62A8
oklch(49.1% 0.131 252.3)
-
Step 800
800
#195088
oklch(42.6% 0.109 252.3)
-
Step 900
900
#1C436D
oklch(37.7% 0.085 252.5)
-
Step 950
950
#112740
oklch(26.9% 0.055 253.1)
#337ECC 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) | #5983CF | 0.039 |
| Deuteranopia (no green cones) | #4275CA | 0.025 |
| Tritanopia (no blue cones) | #00909B | 0.105 |
| Achromatopsia (no color) | #7C7C7C | 0.141 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #337ECC
#337ECC
oklch(58.5% 0.141 252.2)
- #A86D00
#A86D00
oklch(58.4% 0.125 72.1)
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 #337ECC, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Windows Blue #3778BF ΔE 0.023
- Water Blue #0E87CC ΔE 0.027
- Cool Blue #4984B8 ΔE 0.042
- Steel Blue #4682B4 ΔE 0.044
- Nice Blue #107AB0 ΔE 0.049
- Dark Sky Blue #448EE4 ΔE 0.056
- Flat Blue #3C73A8 ΔE 0.058
- Blue NCS #118AB2 ΔE 0.060
Use #337ECC 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.