#337ACE
Closest named color: Windows Blue (#3778BF). oklch(57.7% 0.147 254.7), rgb(51, 122, 206).
Aa
Black text reads best on this color (4.81:1).
About this color
#337ACE is a medium-dark, vivid blue. In OKLCH its lightness is 58%, its chroma 0.147 and its hue 255°. 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 4.81:1.
| Hue family | Blues |
| Lightness | medium-dark (58%) |
| Chroma | vivid (0.147) |
| Temperature | cool |
| Nearest name | Windows Blue (#3778BF) |
| Black text | 4.81:1 |
| White text | 4.36:1 |
Values
| HEX | #337ACE |
| RGB | rgb(51, 122, 206) |
| HSL | hsl(213, 61%, 50%) |
| OKLCH | oklch(57.7% 0.147 254.7) |
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 #337ACE | 4.36:1 | AA large text | Lc -75.3 | Fine for body text |
| Black text on #337ACE | 4.81:1 | AA | Lc 34.2 | Non-text elements, placeholder text |
| #337ACE text on white | 4.36:1 | AA large text | Lc 69.8 | Content text, not long reading |
| #337ACE text on black | 4.81:1 | AA | Lc -31.8 | 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
#F1F6FB
oklch(97.1% 0.009 247.9)
-
Step 100
100
#E1EBF7
oklch(93.6% 0.019 252.9)
-
Step 200
200
#C9DBF2
oklch(88.5% 0.037 254.6)
-
Step 300
300
#A4C3EB
oklch(80.8% 0.066 254.9)
-
Step 400
400
#72A3E2
oklch(70.6% 0.107 255.1)
-
Step 500
500
#4B8BD9
oklch(63% 0.135 254.6)
-
Step 600
600 (this color)
#337ACE
oklch(57.7% 0.147 254.7)
-
Step 700
700
#1E60AC
oklch(49% 0.138 254.9)
-
Step 800
800
#1C4F8B
oklch(42.7% 0.113 254.8)
-
Step 900
900
#1D426F
oklch(37.6% 0.088 254.8)
-
Step 950
950
#122741
oklch(27% 0.056 254.8)
#337ACE 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) | #5281D1 | 0.036 |
| Deuteranopia (no green cones) | #3872CC | 0.021 |
| Tritanopia (no blue cones) | #008E9A | 0.113 |
| Achromatopsia (no color) | #797979 | 0.147 |
Harmonies
Hue rotations in OKLCH that keep this color's lightness and chroma.
Complementary
The opposite hue (180°).
- #337ACE
#337ACE
oklch(57.7% 0.147 254.7)
- #A36D00
#A36D00
oklch(57.7% 0.122 74.8)
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 #337ACE, 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 0.037
- Nice Blue #107AB0 ΔE 0.052
- Cool Blue #4984B8 ΔE 0.053
- Steel Blue #4682B4 ΔE 0.053
- Royal Blue #4169E1 ΔE 0.056
- Flat Blue #3C73A8 ΔE 0.059
- Mid Blue #276AB3 ΔE 0.059
Use #337ACE 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.