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CanvasRenderingContext2D.lineWidth

The CanvasRenderingContext2D.lineWidth property of the Canvas 2D API sets the thickness of lines in coordinate space units.

See also the chapter Applying styles and color in the Canvas Tutorial.

Syntax

ctx.lineWidth = value;

Options

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.

Examples

Using the `lineWidth` property

This is just a simple code snippet using the lineWidth property to draw lines with a rounded end.

HTML

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

JavaScript

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

ctx.beginPath();
ctx.moveTo(20, 20);
ctx.lineWidth = 15;
ctx.lineTo(100, 100);
ctx.stroke();

Edit the code below to see your changes update live in the canvas:

Specifications

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

Browser compatibilityUpdate compatibility data on GitHub

	Desktop
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari
Basic support	Yes	12	Yes	Yes	Yes	Yes

	Mobile
	Android webview	Chrome for Android	Edge Mobile	Firefox for Android	Opera for Android	iOS Safari	Samsung Internet
Basic support	Yes	Yes	Yes	Yes	Yes	Yes	Yes

WebKit/Blink-specific notes

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.