What does the image size analyzer measure?
It measures an image's natural pixel dimensions: the width and height of the image file itself, not the size it happens to be displayed at on a page. You paste a URL, click Analyze, and get one line back, such as 1200 × 630 pixels. It doesn't report file size, format or colour information.
Under the hood the tool creates an image element in your browser, points it at the URL and, once it loads, reads the element's naturalWidth and naturalHeight. Because it never draws the image to a canvas or reads pixel data, cross-origin restrictions don't get in the way. Any image your browser can display, it can measure, whether or not the host sends CORS headers.
Checking an image, step by step
- Copy the image's own address. In most browsers, right-click the image and choose the option to copy the image address.
- Paste it into the input. Spaces at either end are ignored.
- Click Analyze.
- Read the result. Width comes first, then height.
The input takes one URL at a time. Anything an <img> element can load is accepted, including data: URLs, which is how you can measure a local file after converting it with Image to Base64.
Dimension targets worth checking against
The main reason to measure an image is to compare it with a platform's minimums before you publish. These are the published figures for common SEO and social uses:
| Where the image is used | Published guidance | Source |
|---|---|---|
| Google Discover large previews | At least 1200 px wide, more than 300,000 total pixels, 16:9 ratio | Google Discover |
Article structured data image |
At least 50,000 pixels (width × height); 16:9, 4:3 and 1:1 versions recommended | Article markup |
X summary card |
1:1, from 144 × 144 to 4096 × 4096 px | X card docs (archived) |
X summary_large_image card |
2:1, from 300 × 157 to 4096 × 4096 px | X card docs (archived) |
A worked check: an Article image of 300 × 160 pixels has 48,000 pixels in total, just under Google's 50,000 minimum. A 400 × 300 version (120,000 pixels) clears it comfortably. If an image falls short, re-export it from the original at a larger size rather than upscaling the small copy. If it's far larger than any slot it fills, scale it down with the image resizer and then shrink the file with the image compressor.
Reading the number correctly
Natural size is not display size. A 2400 × 1600 photo shown in a 600-pixel-wide column still reports 2400 × 1600. That gap is useful to spot, because every unused pixel is a download your visitors pay for.
The browser reports what it decoded. MDN notes that naturalWidth is density-corrected and that browsers can alter an image before rendering it; Chrome, for example, may lower image resolution on low-end devices, and the property then reports the modified size. On a normal desktop browser the figure matches the file.
Some URLs aren't images. Many "share" and gallery links lead to an HTML page that contains the image. The tool needs the direct file address, usually ending in something like .jpg, .png, .webp or .avif, though CDNs often omit the extension.
When it fails
| What you see | Likely cause | What to try |
|---|---|---|
| Could not load that image URL. | Address is a web page, not an image | Open the page, copy the image address itself |
| Could not load that image URL. | 404, expired signed URL, or login required | Open the URL in a private window to confirm it's public |
| Could not load that image URL. | Host blocks hotlinking from other sites | Measure the downloaded file via a data URL instead |
| 0 × 0 pixels | SVG with no intrinsic width or height | Read the viewBox in the SVG source |
| Nothing happens | Input box empty | Paste a URL first |
There's no timeout in the tool, so an extremely slow host simply leaves you waiting until the browser gives up.
Privacy
The request goes from your browser directly to the server hosting the image, the same way an image embedded in any page would load. Our server never sees the URL. The image host does see a normal browser request from your IP address, so treat it like visiting that URL yourself.
Choosing a preview image for social sharing? Once the dimensions check out, add it to your page with the Open Graph generator.
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