The CanvasRenderingContext2D.shadowBlur property of the Canvas 2D API specifies the amount of blur applied to shadows. The default is 0 (no blur).


ctx.shadowBlur = level;
A non-negative float specifying the level of shadow blur, where 0 represents no blur and larger numbers represent increasingly more blur. This value doesn't correspond to a number of pixels, and is not affected by the current transformation matrix. The default value is 0. Negative, Infinity, and NaN values are ignored.


Using the shadowBlur property

This example uses the shadowBlur property to add a blurred shadow to a rectangle. Note that shadows are only drawn if the shadowColor property is set to a non-transparent value, as well.


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


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

ctx.shadowColor = '#00f';
ctx.shadowBlur = 15;

ctx.fillStyle = '#fee';
ctx.fillRect(20, 20, 140, 100);

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


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

Browser compatibility

Update compatibility data on GitHub
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidiOS SafariSamsung Internet
Basic supportChrome Full support YesEdge Full support 12Firefox Full support YesIE Full support YesOpera Full support YesSafari Full support YesWebView Android Full support YesChrome Android Full support YesEdge Mobile Full support YesFirefox Android Full support YesOpera Android Full support YesSafari iOS Full support YesSamsung Internet Android Full support Yes


Full support  
Full support

In WebKit- and Blink-based browsers, the non-standard and deprecated method ctx.setShadow() is implemented besides this property.

setShadow(width, height, blur, color, alpha);
setShadow(width, height, blur, graylevel, alpha);
setShadow(width, height, blur, r, g, b, a);
setShadow(width, height, blur, c, m, y, k, a);

See also

Document Tags and Contributors

Contributors to this page: mfluehr, fscholz, nmve, erikadoyle
Last updated by: mfluehr,