#337BDB
Closest named color: Windows Blue (#3778BF). oklch(58.8% 0.163 256.9), rgb(51, 123, 219).
Aa
Black text reads best on this color (4.99:1).
About this color
#337BDB is a medium-dark, vivid blue. In OKLCH its lightness is 59%, its chroma 0.163 and its hue 257°. Its hue sits on the cool side of the wheel. The nearest named color is Windows Blue (#3778BF), ΔE 0.043 away. Black text reads best on it, at 4.99:1.
| Hue family | Blues |
| Lightness | medium-dark (59%) |
| Chroma | vivid (0.163) |
| Temperature | cool |
| Nearest name | Windows Blue (#3778BF) |
| Black text | 4.99:1 |
| White text | 4.20:1 |
Values
| HEX | #337BDB |
| RGB | rgb(51, 123, 219) |
| HSL | hsl(214, 70%, 53%) |
| OKLCH | oklch(58.8% 0.163 256.9) |
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 #337BDB | 4.20:1 | AA large text | Lc -74.1 | Content text, not long reading |
| Black text on #337BDB | 4.99:1 | AA | Lc 35.5 | Non-text elements, placeholder text |
| #337BDB text on white | 4.20:1 | AA large text | Lc 68.6 | Content text, not long reading |
| #337BDB text on black | 4.99:1 | AA | Lc -33.1 | 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
#F1F6FC
oklch(97.1% 0.01 252.8)
-
Step 100
100
#E1EBF8
oklch(93.6% 0.021 254.9)
-
Step 200
200
#C8DBF5
oklch(88.5% 0.041 256.2)
-
Step 300
300
#A3C3F0
oklch(80.9% 0.073 256.9)
-
Step 400
400
#70A2E9
oklch(70.6% 0.118 257.2)
-
Step 500
500
#4889E2
oklch(63% 0.15 256.9)
-
Step 600
600 (this color)
#337BDB
oklch(58.8% 0.163 256.9)
-
Step 700
700
#1B5EB4
oklch(49% 0.152 256.9)
-
Step 800
800
#194D92
oklch(42.6% 0.126 257.1)
-
Step 900
900
#1B4174
oklch(37.7% 0.098 256.7)
-
Step 950
950
#112644
oklch(26.9% 0.062 257.5)
#337BDB 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) | #4A84DF | 0.033 |
| Deuteranopia (no green cones) | #2874D9 | 0.021 |
| Tritanopia (no blue cones) | #0092A0 | 0.126 |
| Achromatopsia (no color) | #7C7C7C | 0.163 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #337BDB
#337BDB
oklch(58.8% 0.163 256.9)
- #A57100
#A57100
oklch(58.8% 0.123 76.8)
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 #337BDB, closest first.
Similar named colors
The eight closest entries in our named color list, with their ΔE distance.
- Windows Blue #3778BF ΔE 0.043
- Water Blue #0E87CC ΔE 0.045
- Royal Blue #4169E1 ΔE 0.047
- Clear Blue #247AFD ΔE 0.052
- Cerulean Blue #056EEE ΔE 0.052
- Dark Sky Blue #448EE4 ΔE 0.055
- Soft Blue #6488EA ΔE 0.065
- Cool Blue #4984B8 ΔE 0.066
Use #337BDB 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.