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The CanvasRenderingContext2D.lineWidth property of the Canvas 2D API sets the thickness of lines.

Note: Lines can be drawn with the stroke()strokeRect(), and strokeText() methods.


ctx.lineWidth = value;


A number specifying the line width, in coordinate space units. Zero, negative, Infinity, and NaN values are ignored. This value is 1.0 by default.


Changing line width

This example draws a line and a rectangle, using a line width of 15 units.


<canvas id="canvas"></canvas>


const canvas = document.getElementById('canvas');
const ctx = canvas.getContext('2d');

ctx.lineWidth = 15;

ctx.moveTo(20, 20);
ctx.lineTo(130, 130);
ctx.rect(40, 40, 70, 70);


More examples

For more examples and explanation about this property, see Applying styles and color in the Canvas Tutorial.


Specification Status Comment
HTML Living Standard
The definition of 'CanvasRenderingContext2D.lineWidth' in that specification.
Living Standard  

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
lineWidthChrome Full support YesEdge Full support 12Firefox Full support 1.5IE Full support YesOpera Full support YesSafari Full support YesWebView Android Full support YesChrome Android Full support YesFirefox Android Full support 4Opera Android Full support YesSafari iOS Full support YesSamsung Internet Android Full support Yes


Full support  
Full support
  • In WebKit- and Blink-based Browsers, a non-standard and deprecated method ctx.setLineWidth() is implemented in addition to this property.

Gecko-specific notes

  • Starting Gecko 2.0 (Firefox 4 / Thunderbird 3.3 / SeaMonkey 2.1), setting lineWidth to a negative value no longer throws an exception; instead, it properly ignores non-positive values.

See also