HTMLImageElement: naturalHeight property

An integer value indicating the intrinsic height, in CSS pixels, of the image. This is the height at which the image is naturally drawn when no constraint or specific value is established for the image. This natural height is corrected for the pixel density of the device on which it's being presented, unlike height.

If the intrinsic height is not available—either because the image does not specify an intrinsic height or because the image data is not available in order to obtain this information, naturalHeight returns 0.

This example displays both the natural, density-adjusted size of an image as well as its rendered size as altered by the page's CSS and other factors.

<div class="box">
  <img
    src="/https/developer.mozilla.org/en-US/docs/Web/HTML/Element/img/clock-demo-400px.png"
    class="image"
    alt="A round wall clock with a white dial and black numbers" />
</div>
<pre></pre>

The HTML features a 400x398 pixel image which is placed inside a <div>.

.box {
  width: 200px;
  height: 200px;
}

.image {
  width: 100%;
}

The main thing of note in the CSS above is that the style used for the container the image will be drawn in is 200px wide, and the image will be drawn to fill its width (100%).

const output = document.querySelector("pre");
const image = document.querySelector("img");

image.addEventListener("load", (event) => {
  const { naturalWidth, naturalHeight, width, height } = image;
  output.textContent = `
Natural size: ${naturalWidth} x ${naturalHeight} pixels
Displayed size: ${width} x ${height} pixels
`;
});

The JavaScript code dumps the natural and as-displayed sizes into the <pre>. This is done in response to the images's load event handler, in order to ensure that the image is available before attempting to examine its width and height.