#337BB9
Closest named color: Windows Blue (#3778BF). oklch(56.7% 0.12 247.8), rgb(51, 123, 185).
Aa
Black text reads best on this color (4.67:1).
About this color
#337BB9 is a medium-dark, moderately saturated blue. In OKLCH its lightness is 57%, its chroma 0.120 and its hue 248°. Its hue sits on the cool side of the wheel. The nearest named color is Windows Blue (#3778BF), ΔE 0.014 away. Black text reads best on it, at 4.67:1.
| Hue family | Blues |
| Lightness | medium-dark (57%) |
| Chroma | moderately saturated (0.120) |
| Temperature | cool |
| Nearest name | Windows Blue (#3778BF) |
| Black text | 4.67:1 |
| White text | 4.49:1 |
Values
| HEX | #337BB9 |
| RGB | rgb(51, 123, 185) |
| HSL | hsl(208, 57%, 46%) |
| OKLCH | oklch(56.7% 0.12 247.8) |
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 #337BB9 | 4.49:1 | AA large text | Lc -76.4 | Fine for body text |
| Black text on #337BB9 | 4.67:1 | AA | Lc 33.2 | Non-text elements, placeholder text |
| #337BB9 text on white | 4.49:1 | AA large text | Lc 70.9 | Content text, not long reading |
| #337BB9 text on black | 4.67:1 | AA | Lc -30.8 | 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
#F2F6FA
oklch(97.1% 0.007 247.9)
-
Step 100
100
#E2EBF4
oklch(93.6% 0.016 248)
-
Step 200
200
#CADBEC
oklch(88.4% 0.03 248.2)
-
Step 300
300
#A6C4E2
oklch(80.8% 0.054 248.5)
-
Step 400
400
#75A6D4
oklch(70.8% 0.086 247.6)
-
Step 500
500
#4F8FC9
oklch(63.2% 0.11 247.8)
-
Step 600
600 (this color)
#337BB9
oklch(56.7% 0.12 247.8)
-
Step 700
700
#21649C
oklch(49% 0.112 248)
-
Step 800
800
#1E527F
oklch(42.7% 0.093 248.2)
-
Step 900
900
#1F4466
oklch(37.7% 0.072 248.5)
-
Step 950
950
#13283C
oklch(27% 0.046 248.8)
#337BB9 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) | #5F7EBC | 0.045 |
| Deuteranopia (no green cones) | #4C71B8 | 0.033 |
| Tritanopia (no blue cones) | #008A91 | 0.089 |
| Achromatopsia (no color) | #777777 | 0.120 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #337BB9
#337BB9
oklch(56.7% 0.12 247.8)
- #A46710
#A46710
oklch(56.7% 0.12 68)
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 #337BB9, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Windows Blue #3778BF ΔE 0.014
- Nice Blue #107AB0 ΔE 0.024
- Steel Blue #4682B4 ΔE 0.030
- Flat Blue #3C73A8 ΔE 0.031
- Cool Blue #4984B8 ΔE 0.035
- Water Blue #0E87CC ΔE 0.040
- Muted Blue #3B719F ΔE 0.044
- French Blue #436BAD ΔE 0.045
Use #337BB9 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.