#337CCB
Closest named color: Windows Blue (#3778BF). oklch(58% 0.141 253), rgb(51, 124, 203).
Aa
Black text reads best on this color (4.88:1).
About this color
#337CCB is a medium-dark, vivid blue. In OKLCH its lightness is 58%, its chroma 0.141 and its hue 253°. Its hue sits on the cool side of the wheel. The nearest named color is Windows Blue (#3778BF), ΔE 0.020 away. Black text reads best on it, at 4.88:1.
| Hue family | Blues |
| Lightness | medium-dark (58%) |
| Chroma | vivid (0.141) |
| Temperature | cool |
| Nearest name | Windows Blue (#3778BF) |
| Black text | 4.88:1 |
| White text | 4.29:1 |
Values
| HEX | #337CCB |
| RGB | rgb(51, 124, 203) |
| HSL | hsl(211, 60%, 50%) |
| OKLCH | oklch(58% 0.141 253) |
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 #337CCB | 4.29:1 | AA large text | Lc -74.9 | Content text, not long reading |
| Black text on #337CCB | 4.88:1 | AA | Lc 34.7 | Non-text elements, placeholder text |
| #337CCB text on white | 4.29:1 | AA large text | Lc 69.4 | Content text, not long reading |
| #337CCB text on black | 4.88:1 | AA | Lc -32.3 | 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
#E1EBF6
oklch(93.6% 0.018 250.6)
-
Step 200
200
#C9DBF1
oklch(88.5% 0.036 253.5)
-
Step 300
300
#A4C4E9
oklch(80.9% 0.063 252.3)
-
Step 400
400
#72A4DF
oklch(70.7% 0.102 253.2)
-
Step 500
500
#4B8CD6
oklch(63.1% 0.131 253.2)
-
Step 600
600 (this color)
#337CCB
oklch(58% 0.141 253)
-
Step 700
700
#1D62A8
oklch(49.2% 0.13 252.6)
-
Step 800
800
#1B5088
oklch(42.7% 0.108 252.9)
-
Step 900
900
#1D436D
oklch(37.8% 0.084 252.9)
-
Step 950
950
#122740
oklch(26.9% 0.054 254)
#337CCB 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) | #5782CE | 0.039 |
| Deuteranopia (no green cones) | #3F74C9 | 0.022 |
| Tritanopia (no blue cones) | #008F9A | 0.107 |
| Achromatopsia (no color) | #7A7A7A | 0.141 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #337CCB
#337CCB
oklch(58% 0.141 253)
- #A66D00
#A66D00
oklch(58.1% 0.124 73.2)
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 #337CCB, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Windows Blue #3778BF ΔE 0.020
- Water Blue #0E87CC ΔE 0.031
- Cool Blue #4984B8 ΔE 0.045
- Steel Blue #4682B4 ΔE 0.045
- Nice Blue #107AB0 ΔE 0.047
- Flat Blue #3C73A8 ΔE 0.055
- French Blue #436BAD ΔE 0.059
- Mid Blue #276AB3 ΔE 0.060
Use #337CCB 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.