Image Dimensions Checker
Enter a page to list every image on it, with its real pixel size, the size it's shown at, its file weight, format and alt text. Or drop in your own files to check their dimensions before you upload them.
| Preview | Image | Real size | HTML size | File size | Format | Alt text | Loading | Issues |
|---|
| Preview | File | Dimensions | Ratio | File size | Format | Fits |
|---|
What the checker looks for
| Check | Why it matters |
|---|---|
| Broken images | An image that fails to load shows an empty box or a broken icon, and search engines can't index it. |
| Width and height attributes (HTML size) | They let the browser reserve space before the image arrives. Without them the page jumps as images load, which counts against Cumulative Layout Shift (CLS). |
| Alt text | Screen readers read it out, and search engines use it to understand the image. Decorative images should have an empty alt="", not none at all. |
| Oversized and upscaled files | An image more than twice as wide as its HTML width wastes bandwidth, even on high-density screens. One narrower than its HTML width is stretched and looks soft. |
| File weight | Flagged from 200 KB, and as a warning from 500 KB. These are rules of thumb, not limits Google publishes; a full-width hero photo can reasonably be larger than a thumbnail. |
| Format | WebP and AVIF are usually much smaller than JPEG or PNG at the same quality. |
| Lazy-loading the first image | The first image is often the largest thing above the fold. loading="lazy" delays it and slows Largest Contentful Paint (LCP). |
| Share image size | An og:image under 1200×630 pixels looks soft or small when the page is shared. |
The real size is read by loading each image in your browser. The file size is the bytes your browser downloaded where the image's server allows that to be measured, otherwise the size of the file the server sends a browser, measured by downloading it once. When neither is available it shows as unknown rather than an estimate.
Common image sizes
| Use | Size |
|---|---|
| Open Graph share image | 1200×630 pixels (1.91:1) |
| Google Discover | At least 1200 pixels wide, with large image previews allowed |
| Article structured data | At least 50,000 pixels (width × height), in 16:9, 4:3 and 1:1 versions |
| Apple touch icon | 180×180 pixels |
| Web app manifest icons | 192×192 and 512×512 pixels |
Questions
How do I check the dimensions of an image online?
Switch to Your own files and drop the image in. Its width, height, aspect ratio and file size appear straight away, and nothing is uploaded. To check images already on a website, enter the page's URL instead.
What's the difference between the real size and the attributes?
The real size is the image file's own width and height in pixels. The width and height attributes in the HTML say how much space to reserve for it. They don't have to match, but if the file is much larger than the space it fills, visitors download pixels they never see.
What is the best image size for a website?
There's no single answer. Make each image about as wide as the largest size it's shown at, doubled for high-density screens, and compress it. A full-width hero might be 1600 to 2400 pixels wide; a thumbnail shown at 300 pixels needs about 600.
Why are some images missing from the list?
The checker reads the page's HTML. Images added later by JavaScript, and images set as CSS backgrounds, aren't in the HTML, so they aren't listed. Lazy-loaded images that keep their real address in data-src are included.