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

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.

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

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

• The interface defining this property: CanvasRenderingContext2D
• CanvasRenderingContext2D.lineCap
• CanvasRenderingContext2D.lineJoin
• Applying styles and color