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SEO Guide · Chapter 15 of 30
How to write alt text for the photos on your site
This page is for the owner of a local business site that runs on photos, such as listings and galleries. After reading it you will be able to write alt text that describes a photo and find every image that has none.
In one paragraph
Alt text is a short written description attached to each photo on your site, and it should say what is in the picture in plain words, including the place and the subject, in about eight to fifteen words. Google cannot see a photo and reads the alt text instead, so a listing photo with the alt text IMG_4471 tells it nothing while one that reads 160 acres of irrigated farm ground near Rexburg puts the page in image search and helps the page rank. Write it for a person who cannot see the picture and you will get it right.
What alt text is
Alt text is a line of text stored with each image on a page, in the HTML as alt="...". It was created so that a screen reader could describe the picture to someone who cannot see it, and that is still its first job. It is not the caption under the photo and it is not the file name, though when it is blank the file name is what Google falls back on.
Google reads alt text to understand what a photo shows and, through that, what the page is about. A page with twenty photos of custom kitchens and twenty blank alt attributes is, to Google, a page with twenty unknown rectangles. The same page with twenty short descriptions is a page that clearly concerns kitchens in a named town, and each of those photos can appear in Google Images with a link back to the page.
Good alt text names what is in the picture, the place if the place matters, and nothing else. It does not begin with the words image of or photo of, since Google and the screen reader already know it is an image, and it does not repeat a keyword five times.
What missing alt text looks like on a land brokerage site
Upper Valley Land Company in Rexburg lists farm ground, ranches and recreational parcels across eastern Idaho, and every listing page is built around photos. A 160-acre irrigated parcel south of town listed at $1.52 million has 24 photos: aerials, pivot lines, the canal headgate, the county road frontage and the view toward the Tetons.
Every one of those photos was uploaded with the alt text left blank, so the file names DJI_0342, DJI_0343 and IMG_4471 stand in for it. Across the whole site, 214 photos are live, 171 have no alt text at all, 38 carry a file name that was pasted in, and 5 were written by hand two years ago.
The consequence shows in two places. Google Images returns nothing from the site for farm ground for sale Rexburg. And the listing page itself, which has 90 words of text and 24 photos, gives Google very little to rank. The words that would make the page match the search, irrigated, pivot, acres, Rexburg, are in the photos and not in the text, and Google cannot see the photos.
A worked example: describing the listing photos for a Rexburg land broker
Every image on the site was counted by its alt text state, and the listing photos were written first because they carry the pages that bring in buyers. The counts are in the first table and six photos from the 160-acre listing are in the second.
| Alt text state | Images before | Images after |
|---|---|---|
| Blank | 171 | 0 |
| File name pasted as alt | 38 | 0 |
| Written description | 5 | 196 |
| Empty on purpose, decorative | 0 | 18 |
| Total | 214 | 214 |
| Photo | Alt text before | Alt text after |
|---|---|---|
| Drone aerial of full parcel | DJI_0342 | Aerial view of 160 acres of irrigated farm ground south of Rexburg, Idaho |
| Center pivot | DJI_0347 | Center pivot irrigation system on the north 80 acres |
| Canal headgate | IMG_4471 | Canal headgate and water right delivery point on the east boundary |
| Road frontage | IMG_4478 | Paved county road frontage along the west side of the parcel |
| Teton view | IMG_4490 | View east toward the Teton Range from the parcel |
| Plat map | plat-final-v3 | Plat map of the 160-acre parcel with section lines and access easement |
The 18 images marked decorative are the logo in the footer, the icons beside the phone number and a background texture. Those were given an empty alt attribute on purpose, which tells a screen reader to skip them, rather than a description nobody needs.
Each written description names what the photo shows and, where it helps, where it is. The town appears once, on the aerial, because the page already says Rexburg in the heading and repeating it in all 24 photos would read as stuffing. The words a buyer searches for, irrigated, pivot, water right, county road, now appear in the page for the first time, attached to the photo that proves them.
How to check your own alt text
- Open any page on your site, right-click a photo and choose Inspect. The highlighted line shows the image tag. Look for
alt=. If the attribute is missing or reads as a file name, the photo has no useful description. - In WordPress, go to Media, then Library, click any image and look at the field labeled Alternative Text. On a site with hundreds of images, the free version of Screaming Frog SEO Spider will crawl the site and, under the Images tab, filter to Missing Alt Text with the page each one sits on.
- Search Google Images for a search you want to win, such as farm ground for sale Rexburg, and look for your own photos. If none appear, alt text is the usual reason.
- Check the photos in your page builder widgets as well as the media library, since a photo placed inside a slider or gallery widget often has its own alt field that overrides the library one.
A gallery that loads only on desktop carries no alt text at all, and the mobile-first indexing page explains how to check for that.
What we do about alt text
You will get a count of every image on your site by its alt text state, blank, file name or written, followed by a written description for every photo that carries meaning and an empty attribute for every one that is decorative. Descriptions are written from the photo itself and from the page it sits on, so they say what is there and never guess. Gallery and slider widgets are checked separately from the media library so nothing is missed. The audit that starts every engagement counts the blanks first.
Questions people ask about SEO: how to write alt text for the photos on your site
What should alt text say?
Alt text should say what is in the photo in plain words, with the place if it matters, in about eight to fifteen words, such as center pivot irrigation on 80 acres near Rexburg. Do not start with image of or photo of. Do not stuff it with keywords the picture does not show.
Does alt text help SEO?
Yes, alt text helps SEO because Google cannot see a photo and uses the alt text to understand what it shows and what the page is about, and it is the main way a photo gets into Google Images with a link to your page. On a photo-heavy page such as a listing or a gallery, the alt text can carry most of the page's meaning.
How long should alt text be?
Alt text should be one sentence, usually eight to fifteen words and rarely more than 125 characters, because older screen readers cut it off at that point. A plat map or a chart may need a little more.
Should every image have alt text?
Every image that carries meaning should have written alt text, and every image that is decorative, such as a background texture or a divider, should have an empty alt attribute so screen readers skip it. Leaving the attribute out entirely is the one thing not to do, because then the reader hears the file name instead.
Can I use the same alt text for multiple images?
No, each photo should have its own description, because two photos with the same alt text tell Google and a screen reader that they are the same picture. Photos of the same subject can share words but should differ in what they name. Five photos of a kitchen should say which part of the kitchen each one shows.
This page is part of the The SEO guide for local businesses. The other guides: SEO, AEO, GEO.
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