SEO finding
An image is broken, heavier than needed or missing attributes
SEO Warning Severity: Medium
Part of the audit Images. Finding id: seo.imageProblems.
What it costs you
Broken images leave holes in the page. Heavy images slow it down. Images without alt text are invisible to image search and to screen reader users.
What to do
Fix the image once at its source; every page that uses it is fixed with it.
What it checks
- Images without description text
- Images without set size
- Image files too large
- Images not adapted to screen size
- Images shown squashed or stretched
- Outdated image format
- Image does not load
- Image address redirects elsewhere
How to fix it
Repair the image address
- Open [src]. If it answers with an error, put the file back or remove the img element from [example page] and the other pages.
- If it redirects, write the address it ends at into the src.
How to check: curl -sI [src] shows status 200. Recrawl the pages that use the image.
Add an alt attribute
- Open [example page] and look at what the image shows and why it is there.
- Write that in a few words in the alt attribute. Do not start with "image of".
- Decoration: set alt="" so screen readers skip it.
How to check: Recrawl the pages that use the image and run this rule again.
Set width and height
- Use the real pixel size of the file. CSS can still scale the image.
How to check: Recrawl the pages that use the image and run this rule again.
Serve a smaller file
- Export the image no wider than about twice the widest size it is shown at, in WebP or AVIF.
- Export one or two smaller widths and list them in srcset.
How to check: Recrawl the pages that use the image and run this rule again.
Thresholds
| Name | Default | Meaning |
|---|---|---|
max_scale | 2.0 | An image is oversized when its real width is more than this many times the widest size it is shown at. 2 leaves room for high-density screens. |
oversized_min_bytes | 50000 | Oversized images below this file size are not reported; the saving is too small. |
responsive_min_width | 800 | Images at least this wide in pixels are expected to offer smaller versions through srcset. |
aspect_tolerance | 0.05 | How far the shape of the box may differ from the shape of the image file, as a share of the file's width to height ratio. |
legacy_min_bytes | 100000 | JPEG, PNG, GIF, BMP and TIFF files below this size are not reported as legacy format. |