Image size checker: find the heavy images that slow your page down
This image size checker finds the heaviest images on a page and lists each one with its file size, format, real and displayed dimensions, and whether it is too heavy, too big or missing width and height.
- Free, no account
- Results in under a minute
- Up to 100 images per page
Example result:example-shop.hr
WordPress 6.8Sample shop · homepage · mobile Chrome · the same check you get for your own site
Detected technology
- WordPress 6.8
- WooCommerce
- Elementor
- jQuery 1.12.4
- LiteSpeed
Images on this page
4 images · 1831 KB total| Image | Size | Format | Pixels | Set in HTML | Loading | Status |
|---|---|---|---|---|---|---|
| example-shop.hr/assets/hero-large.pngno alt | 1829 KB | png | 1200×520 | no width/height set | eager | 200 |
| example-shop.hr/assets/img-300x300.pngno alt | 1 KB | png | 300×300 | no width/height set | eager | 200 |
| example-shop.hr/assets/img-160x40.pngno alt | 1 KB | png | 160×40 | 160×40 | eager | 200 |
| example-shop.hr/assets/img-100x30.pngno alt | 1 KB | png | 100×30 | no width/height set | eager | 200 |
What we found
Show 5 passed checks
Fix these first
From the example above. Check your own site to get the fixes that apply to it.
Problem: 15 images have no alt attribute
Alt text is how Google Images and screen readers understand a picture.
How to fix it: Describe each meaningful image in a short alt attribute ("Blue running shoe, side view").Warning: 4 images weigh 1831 KB (largest 1829 KB)
Images are usually the heaviest part of a page.
How to fix it: Resize images to the size they are shown at (a 400 px wide photo does not need a 4000 px file).Warning: 1 image is larger than 300 KB
A single image over a few hundred kilobytes takes longer to download on mobile than the rest of the page.
How to fix it: Export each listed image at the size it is displayed and save it as WebP or AVIF at about 80 % quality.
What the image size checker looks at
Each image measured from the file itself, plus the total image weight the browser loads.
Heavy image files
Finds single images that are too large in file size and slow the page down on mobile.
Oversized images
Finds images served at more than twice their displayed size, which wastes visitors' data.
Images without width and height
Finds images without width and height, which make the text jump as the page loads.
Broken images
Finds images that fail to load and leave an empty space or placeholder for every visitor.
Total image weight
Adds up the size of all images on the page, usually the heaviest part and slowest on mobile.
Images without alt text
Finds images with no alt text, which Google Images and screen readers need to understand them.
Modern image formats
Checks images use WebP or AVIF, which are much smaller than JPEG and PNG at the same quality.
Image sizing
Finds images sent larger than the space they are shown in, wasting bytes on every visit.
Offscreen image loading
Checks images below the fold wait until scrolled to, so the visible ones load first.
Show 5 more checks
Total image weight
Adds up the size of all images on the page, usually the heaviest part and slowest on mobile.
Images without alt text
Finds images with no alt text, which Google Images and screen readers need to understand them.
Modern image formats
Checks images use WebP or AVIF, which are much smaller than JPEG and PNG at the same quality.
Image sizing
Finds images sent larger than the space they are shown in, wasting bytes on every visit.
Offscreen image loading
Checks images below the fold wait until scrolled to, so the visible ones load first.
How the image size checker works
Read each image
Up to 100 image sources are requested. The first 64 KB of each gives its format and pixel size, and Content-Length gives its file size.
Compare with the HTML
Using the width, height, loading and srcset attributes, we flag files over 300 KB, images over twice their displayed size, missing dimensions and failed loads.
Load the page in Chromium
Chromium loads the page without scrolling, so the total image weight includes CSS backgrounds, and Lighthouse adds its format and sizing estimates.
The per-image table lists <img> tags found in the HTML. CSS backgrounds and images added by scripts count in the total but get no row of their own.
Image size checker questions
How do I find the heaviest images on a page?
Enter the page address above. The checker requests up to 100 images from the HTML and lists each with its file size, format, real and displayed dimensions, flagging files over 300 KB, images more than twice their displayed size and images without width and height. In Chrome, the Network panel filtered to Img and sorted by size shows the same for one visit.
Why are images up to twice their displayed size not flagged?
Because high-density screens need them. A phone or laptop with a 2x display draws an image shown 400 CSS pixels wide with 800 real pixels, so an 800-pixel file is the right size there. The checker flags only images more than twice their displayed size, where even those screens discard pixels. Add srcset and sizes so smaller and 1x screens get a lighter file as well.
Why should images have width and height attributes?
So the browser can reserve the right space before the image loads. Without them, text below jumps down when the image arrives, which counts against Cumulative Layout Shift, a Core Web Vital. Set width and height to the image's real pixel size and let CSS scale it with height: auto; the browser keeps the ratio. The checker lists every image missing them.
Does it check CSS background images?
Partly. CSS background images count in the total image weight, because Chromium loads the page and records every image it downloads, but they get no row of their own, since the table lists the img tags in the HTML. To find a heavy background image, open the Network panel in your browser's developer tools, filter to Img and sort by size.
Can it tell me the dimensions of an image?
Yes, for every image on a web page. The checker reads the first 64 KB of each file to get its real pixel width and height, and compares them with the size the HTML displays it at. For a single file on your computer, your file browser's info panel shows the dimensions; this tool is for images already on a page.
Why is the total in the report higher than the table?
The table lists the img tags found in the HTML, up to 100. The total comes from Chromium loading the page, so it also counts CSS background images, favicons and images added by scripts. When the gap is large, look at CSS backgrounds and sliders: they get no row of their own but still cost bytes.
Is this image size checker free?
Yes, with no sign-up. getReport is funded by donations, not plans, and the complete report with all seven modules is one click away, also free. It stays at its shareable link for 12 months, is not listed publicly and carries a noindex tag, and nothing about your visitors is collected.
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