Centered canvas element in HTML5

October 29, 2011

If you want a fixed-sized canvas element on an otherwise blank page, the following markup and code might be interesting for you:

<!DOCTYPE html>
<html lang="en">
    <meta charset="utf-8" />
      body { background-color: black; }
      #cvs { background-color: white; }
      // the desired canvas dimensions
      var canvasWidth = 500;
      var canvasHeight = 500;

      function init() {
        var cvs = document.getElementById("cvs");

        // compute margins
        var marginLeft = (window.innerWidth-canvasWidth)/2;
        var marginTop = (window.innerHeight-canvasHeight)/2;

        // set canvas dimensions
        cvs.width = canvasWidth;
        cvs.height = canvasHeight;
        // set css properties
        cvs.style.marginLeft = marginLeft+"px";
        cvs.style.marginTop = marginTop+"px";

  <body onload="init();">
    <canvas id="cvs"><canvas>

The style in the code is only there to make the result instantly visible. If you want to make the canvas element recenter on a resize event, you just need to bind a function to the window.onresize event. However, if you want to resize the canvas elements dynamically, remember that the drawn content gets erased. See this snippet for a related example.

Join the Mailing List

Subscribe to get weekly updates and my latest articles by email.

    (About the content, privacy, analytics and revocation).

    We won't send you spam. Unsubscribe at any time.

    Powered By ConvertKit