CanvasRenderingContext2D.lineWidth

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.

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

Changing line width

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

HTML

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

JavaScript

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

ctx.lineWidth = 15;

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

Result

More examples

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

Specifications

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

Browser compatibility

BCD tables only load in the browser

  • 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