Every image on your WordPress site has a small text field that most people skip: the alternative text, or alt text. It is read aloud by screen readers, shown when an image fails to load, and used by search engines to understand what a picture shows. On a busy site with hundreds of uploads, writing it by hand for every file rarely happens, which is why so many people search for a way to auto generate image alt text in WordPress.

Automation helps, but it is worth knowing exactly what it can and cannot do. This guide covers what good alt text looks like, the two main ways tools generate it, a manual workflow for the images that matter, and how the free Impex Rank SEO plugin fills the gaps.

What good alt text actually is

Alt text exists first for accessibility. The Web Content Accessibility Guidelines (WCAG) ask that every non-text element has a text alternative that serves the same purpose. SEO benefits are a side effect of doing that well, not the other way round.

A useful way to write it: imagine you are reading the page aloud to someone on the phone. What would you say about this image so they do not miss anything?

  • Describe the purpose, not just the pixels. A photo of a red kurta on a product page should say "Red cotton kurta with mirror work, front view", not "image of clothing".
  • Keep it short. One sentence, usually under about 125 characters. Long explanations belong in a caption or the body text.
  • Do not start with "image of" or "picture of". Screen readers already announce that it is an image.
  • Linked images describe the destination. If your logo links to the home page, "Sharma Dental Clinic home" is more helpful than "logo".
  • Charts and diagrams need the takeaway. "Bar chart showing monthly orders doubling between April and June" tells the reader what the image is there to say.

Decorative images get an empty alt

Dividers, background flourishes and stock photos that add mood but no information should have alt="". An empty alt attribute tells screen readers to skip the image. A missing alt attribute is different: some screen readers then read out the file name, which is worse.

Do not stuff keywords

Alt text is not a hidden keyword box. If your focus keyword genuinely describes an image, use it. If you add "best wedding photographer in Pune" to twenty images on one page, you make the page harder to use for anyone relying on a screen reader and you gain nothing. Search engines have long treated that pattern as spam.

Two ways to generate alt text automatically

There are broadly two approaches, and they have very different trade-offs.

1. File name and title based

The tool takes the attachment title (which WordPress creates from the file name) and turns it into readable text. red-cotton-kurta-front.jpg becomes "Red cotton kurta front".

Pros: instant, free, works offline, and no image or data leaves your server. Cons: it is only as good as your file names. IMG_20260912_104512.jpg produces useless alt text.

2. AI vision based

The tool sends each image to a computer-vision or multimodal AI service, which returns a description.

Pros: it can describe what is actually in the picture, even with a bad file name. Cons: it usually costs money per image, sends your images to a third party, can be confidently wrong (misidentifying products, people or places), and knows nothing about context. It cannot know that the photo of a building is your clinic in Rajkot.

Neither approach replaces a human for images that matter. Automation is a safety net that makes sure nothing is left empty; your judgement is what makes the important ones good.

The manual workflow (no plugin needed)

For the images that carry real meaning, such as products, team photos, infographics and screenshots, do this:

  1. Go to Media → Library and switch to list view.
  2. Click an image to open Attachment details.
  3. Fill in Alternative Text. WordPress saves it automatically.
  4. In the block editor, select an image block and check the Alternative text field in the sidebar under Settings. Text set here applies to that use of the image.

Note that alt text set in the Media Library is used as the default when you insert the image. If you inserted an image before adding alt text, the existing block may still have an empty alt, so check older posts.

A sensible bulk approach

You do not need to fix 2,000 images in one evening. Prioritise:

  1. Product and service images on pages that earn money.
  2. Images on your top 20 pages by traffic (check Google Search Console or your analytics).
  3. Infographics, charts and screenshots, because their information is otherwise invisible.
  4. Everything else can rely on automatic alt text until you get to it.

Rename files before you upload

The single cheapest improvement you can make is to name files properly before uploading. It improves automatic alt text, makes your Media Library searchable, and gives image search a small extra signal.

  • Use lowercase words separated by hyphens: stainless-steel-water-bottle-1-litre.jpg.
  • Describe the content, not the camera: avoid IMG_4821.jpg or WhatsApp Image 2026-10-01.jpeg.
  • Keep it short and specific. Four to six words is plenty.
  • Compress before upload. A descriptive name on a 4 MB photo still hurts your page speed.

Make it a team habit. If staff upload photos straight from a phone or WhatsApp, a two-minute rename step saves hours of alt text work later.

Doing it with Impex Rank SEO

Impex Rank SEO is a free WordPress SEO plugin, and its Image SEO module takes the file name and title based approach. It is worth being clear about this: it is not computer-vision AI, and it does not send your images anywhere.

Here is what it does:

  • On upload: when you upload an image and the alt text is empty, the plugin fills it from the attachment title, made readable. The file extension is removed and hyphens and underscores become spaces. Alt text you have already written is never touched.
  • On render: if an image is output through WordPress's attachment image functions (typically featured images and images your theme prints) with an empty alt attribute, the plugin backfills it the same way, including for images uploaded before you installed the plugin. Images already embedded in post content keep the alt text saved in that content, so use the analyser's Fix button or the optimiser for those.
  • In the analyser: the SEO meta box in the post editor checks whether images in your content have alt text. The Fix button on that check writes alt text that combines the post title with your focus keyword, instead of repeating the same title on every image.
  • Site wide: the one-click optimiser on the Optimization screen can fill missing alt text across your posts and pages, along with missing meta descriptions and focus keywords. On the free plugin that optimiser has an allowance of three optimised posts per calendar month; editing alt text yourself is always free and unlimited.

Because the plugin works from titles, the advice above about renaming files matters even more. Good file names in, good alt text out.

Where Pro fits

The optional Impex Rank SEO Pro add-on generates featured images for AI-written posts, either with an image-capable AI provider or from free stock libraries, and writes alt text for those images. It also removes the monthly cap on the one-click optimiser. None of that is needed for the Image SEO module itself, which is free.

Review the important ones

Automatic alt text is a floor, not a ceiling. Once the plugin is active:

  1. Open your most important pages and view the source, or use your browser's accessibility inspector, to see the alt text in use.
  2. Rewrite anything that is vague, repetitive or wrong.
  3. Decide what to do with purely decorative images. Automatic tools, this plugin included, tend to fill an empty alt, so a divider or flourish that should be silent is often better added as a CSS background or through your theme, and worth checking after any bulk fix.

A quick checklist

  • [ ] Descriptive, hyphenated file names before upload
  • [ ] Hand-written alt text on product, service and information-bearing images
  • [ ] Empty alt on purely decorative images
  • [ ] Keyword only where it honestly describes the image
  • [ ] Automatic alt text switched on as a safety net for everything else
  • [ ] Spot-check your top pages every few months

Frequently asked questions

Can WordPress generate alt text automatically?

WordPress core does not write alt text for you. A plugin can fill it in, either from the file name and attachment title or by sending the image to an AI vision service. Impex Rank SEO uses the attachment title and file name, so nothing leaves your site.

Is automatic alt text good enough for SEO?

It is far better than empty alt attributes, and it is good enough for most incidental images if your file names are descriptive. For product photos, charts and images that carry meaning, review the automatic text and rewrite it by hand.

Should decorative images have alt text?

No. Purely decorative images such as dividers and background flourishes should have an empty alt attribute so screen readers skip them. Describing them only adds noise for people using assistive technology.

Should I put my focus keyword in every alt attribute?

No. Use the keyword where it honestly describes the image. Repeating the same phrase on every image is keyword stuffing, it does not help rankings and it makes the page worse for screen reader users.

Get started

Install Impex Rank SEO free from WordPress.org, or in your WordPress admin go to Plugins → Add New and search for "Impex Rank SEO". Image SEO is switched on from the start. See every module on the features page, and read the related guide on making your WordPress site ready for AI search.