#337BBC
Closest named color: Windows Blue (#3778BF). oklch(56.9% 0.123 249), rgb(51, 123, 188).
Aa
Black text reads best on this color (4.70:1).
About this color
#337BBC is a medium-dark, moderately saturated blue. In OKLCH its lightness is 57%, its chroma 0.123 and its hue 249°. Its hue sits on the cool side of the wheel. The nearest named color is Windows Blue (#3778BF), ΔE 0.011 away. Black text reads best on it, at 4.70:1.
| Hue family | Blues |
| Lightness | medium-dark (57%) |
| Chroma | moderately saturated (0.123) |
| Temperature | cool |
| Nearest name | Windows Blue (#3778BF) |
| Black text | 4.70:1 |
| White text | 4.46:1 |
Values
| HEX | #337BBC |
| RGB | rgb(51, 123, 188) |
| HSL | hsl(208, 57%, 47%) |
| OKLCH | oklch(56.9% 0.123 249) |
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 #337BBC | 4.46:1 | AA large text | Lc -76.2 | Fine for body text |
| Black text on #337BBC | 4.70:1 | AA | Lc 33.4 | Non-text elements, placeholder text |
| #337BBC text on white | 4.46:1 | AA large text | Lc 70.7 | Content text, not long reading |
| #337BBC text on black | 4.70:1 | AA | Lc -31.0 | 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
#F2F6FA
oklch(97.1% 0.007 247.9)
-
Step 100
100
#E2EBF4
oklch(93.6% 0.016 248)
-
Step 200
200
#CADBED
oklch(88.4% 0.031 249.7)
-
Step 300
300
#A5C4E4
oklch(80.8% 0.056 249.4)
-
Step 400
400
#74A5D6
oklch(70.6% 0.089 249.2)
-
Step 500
500
#4E8ECB
oklch(63.1% 0.114 249)
-
Step 600
600 (this color)
#337BBC
oklch(56.9% 0.123 249)
-
Step 700
700
#21649E
oklch(49.1% 0.114 248.8)
-
Step 800
800
#1D5280
oklch(42.7% 0.094 248.4)
-
Step 900
900
#1E4467
oklch(37.7% 0.074 248.7)
-
Step 950
950
#13283C
oklch(27% 0.046 248.8)
#337BBC 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) | #5D7EBF | 0.043 |
| Deuteranopia (no green cones) | #4A71BB | 0.031 |
| Tritanopia (no blue cones) | #008A93 | 0.090 |
| Achromatopsia (no color) | #777777 | 0.123 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #337BBC
#337BBC
oklch(56.9% 0.123 249)
- #A56702
#A56702
oklch(56.8% 0.123 68.8)
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 #337BBC, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Windows Blue #3778BF ΔE 0.011
- Nice Blue #107AB0 ΔE 0.027
- Steel Blue #4682B4 ΔE 0.032
- Flat Blue #3C73A8 ΔE 0.034
- Cool Blue #4984B8 ΔE 0.035
- Water Blue #0E87CC ΔE 0.037
- French Blue #436BAD ΔE 0.046
- Muted Blue #3B719F ΔE 0.048
Use #337BBC 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.