Speed
Images reserve their space before loading
performance.images-missing-dimensions
Why this matters
The browser cannot tell how tall these images will be until they have downloaded, so it draws the page without them and then pushes everything down when they arrive. That is the jump people experience as a page moving under their thumb.
Who fixes it
You can, usually
Roughly how long
Minutes
Care needed
Low risk to change
How to fix it
Add `width` and `height` attributes matching the image's real pixel dimensions. CSS can still resize it — the attributes only tell the browser the shape to reserve.
On your platform
WordPress
The block editor adds these automatically for images inserted from the Media Library, so the ones missing them are nearly always pasted into a custom HTML block, or placed by a page builder that writes its own markup. Re-inserting the image as a proper image block is quicker than editing the attributes, and it keeps working when the image is replaced.
Shopify
Current Shopify themes render images through the `image_tag` filter, which adds width and height for you. A missing pair therefore means a hand-written `<img>` in a custom section or snippet, or an app block — Online Store → Themes → Edit code and search the sections for `<img`.
Drupal
Images rendered through an image field and an image style get their dimensions automatically. The ones without are images placed into a body field through the editor, where the dimensions depend on what the editor wrote — so this is a content fix rather than a theme one.
Joomla
The editor's image dialog has Width and Height fields, and they are frequently cleared out by whoever inserted the image because the picture looked too big. Set them back to the file's real pixel size and use CSS to make it smaller; the attributes are what reserve the space, not what size it appears.
How we score it
Failing this check takes up to 12 points off your speed score. It is a fact about your site rather than a measurement, so it reads the same on every scan until you change something.
Does your site pass this one?
This check runs on every scan, along with the other 106. Free, no account, and you see the evidence for each result.
Check my siteOther speed checks
- Every page gets the files it asks forA file that is missing on one template is missing on every page built from it, which is usually hundreds of pages rather than one. It is also the hardest kind to notice from the inside: a browser that has an older copy of the file will carry on showing it long after the file itself has gone, so the site looks correct to whoever built it and broken to everybody arriving fresh.
- Every page responds promptlyWhen one part of a site responds noticeably slower than the rest, it usually points at one specific thing rather than at the hosting in general — a heavy search query, an unindexed database lookup, or a page rebuilding something on every request. That makes it one of the more fixable speed problems, because there is a single cause to find.
- Everything the page asks for loadsYour page requests these and gets nothing back. Depending on what they are, that means a missing image, a stylesheet that never applies, or a script that never runs — and the page may look fine to you if your browser has an older copy cached.
- First visit after a quiet spell is not slowSome hosting puts a site to sleep when nothing has visited for a while, and the next request has to wake it. Once warm the site is fine, which is why this is easy to miss — the person testing it has usually just loaded the page. The people who get the slow version are the ones arriving overnight, and Google when it crawls at an odd hour.
- Google has enough visitor data to report on your siteGoogle publishes real-visitor speed figures for a site only once enough Chrome users have been there to make the numbers meaningful and anonymous. Below that threshold there is nothing to publish, which is the ordinary situation for a small business site and says nothing about how well the site is built. It does mean every speed figure in a report like this one is a simulation rather than a record of what happened to anybody.
- Main content appears quickly on a phoneThe largest thing on the page — usually the main image or headline — is what a visitor is waiting for. Until it finishes loading they are looking at a blank or half-built page. This is measured on a mid-range phone on mobile data rather than on a fast desktop connection, because that is the harder case and the one most visitors are actually in.