78% of images on a typical ecommerce site have empty alt text. That’s not a guess: it’s from a 500-page, 3,000-image audit I read through last week. Only 7% had anything actually descriptive.
Most of you reading this fall into that 78%.
What Alt Tags Actually Are (Not the Textbook Definition)
An alt tag, also called alt text or the alt attribute, is HTML that sits inside your image tag and describes what the picture shows. Something like this:
<img src="ankle-boot.jpg" alt="women's black leather ankle boots with 2-inch heel">Search engines are blind. Literally. Googlebot can’t look at your product photo and go “nice boots.” It reads the alt attribute instead, and that text is how the crawler decides what the image is and where it belongs in search results.
Screen readers use the same text to describe images to visually impaired shoppers. So alt tags are doing double duty, accessibility and SEO, with one line of code.
There’s also a caption vs. alt text mix-up worth clearing up. A caption is visible copy underneath an image, meant for the reader. Alt text is invisible unless the image fails to load or a screen reader is running. Both can help SEO, but they’re not interchangeable, and stuffing your caption text into the alt attribute (or vice versa) usually reads as unnatural to both users and crawlers.
Why Ecommerce Stores Can’t Ignore This
Here’s the part most guides skip: Google Images is a real traffic channel, not some afterthought. It reportedly accounts for over 20% of all web searches. For a store with hundreds of product photos, that’s a huge chunk of discovery you’re leaving on the table if every image is tagged “product-1.jpg” or nothing at all.
I’ve seen this play out with clients. One had a product line that barely showed up anywhere in Google Images. We rewrote alt text on 40 of the top-selling SKUs. Three weeks later, image search impressions on those pages jumped. Not overnight magic, just Google finally understanding what was in the photos.
It’s not only about search, either. Shoppers browsing on slow connections or older devices sometimes see broken image icons instead of your product photo. Good alt text at least tells them what they’re missing: “matte black ceramic mug, 12oz” beats a blank box with a question mark.
What Bad Alt Text Looks Like (You Probably Have Some)
Go check your own site right now. I’ll wait.
Found any of these?
- Empty alt attributes (
alt="") on product photos - Filenames dumped straight in:
alt="IMG_2847.jpg" - One-word lazy tags:
alt="shoes"oralt="watch" - Keyword-stuffed nightmares:
alt="shoes boots footwear cheap shoes buy shoes online" - Copy-pasted tags across every color variant, so five different mugs all say
alt="mug"
That last keyword-stuffed example isn’t just ugly, it can actively hurt you. Cramming keywords into the alt attribute makes it unreadable, and search engines may penalize it. Google’s whole goal is matching intent to content. A wall of keywords signals manipulation, not description.
How to Write Alt Text That Actually Works
Forget the generic advice. Here’s what separates alt text that works from alt text that’s just there:
- Name the product type first: boot, mug, backpack, whatever it is.
- Add the distinguishing details: color, material, size, style.
- Skip “image of” or “picture of”, screen readers already announce it’s an image.
- Keep it under 125 characters. Screen readers may truncate longer text, and search engines don’t need a paragraph.
- Match it to page context: a coffee mug on a “gifts for coworkers” page can mention that angle.
- Never repeat identical alt text across variants: a red mug and a blue mug need different tags, not the same one twice.
- Write for a human first: if it wouldn’t make sense read aloud, rewrite it.
Real before/after, straight from my own product catalog work:
❌ “mug” ✅ “matte black ceramic coffee mug, 12oz, dishwasher safe”
That second version tells Google exactly what’s for sale and gives a screen reader user the full picture in one sentence.
Renaming your image files matters here too. A file named “blue-ceramic-coffee-cup.jpg” gives search engines context before they even reach the alt text. Small habit, real impact when you’ve got a few hundred SKUs. Pair a clean filename with a specific alt tag and you’ve covered two ranking signals for the price of one habit change.
Where Alt Tags Rank in Your SEO Priority List
Here’s the contrarian bit. Alt tags matter, but they’re not where you start.
Alt tags shouldn’t outrank your title tags, internal linking, and meta descriptions. They’re the detail work. Prioritize them hardest on image-heavy pages that are light on actual text: your homepage hero, category landing pages, and your top 20 or so product pages. That’s where the ratio of “image weight to text weight” makes alt text pull real SEO weight.
Everywhere else, do it because it’s good practice. Just don’t burn a week rewriting alt text on your blog’s decorative background images while your product titles are still generic garbage. Fix the bigger levers first, then come back for the polish.
Doing This at Scale Without Losing Your Mind
If you’ve got 3,000 product images, nobody’s writing all of that by hand. I wouldn’t either.
The realistic move: use an AI alt-text tool to bulk-tag everything, then manually review and refine your top-performing pages, the ones actually driving revenue. One case study I came across bulk-optimized 3,000 images with AI, then manually refined the top 200 product hero images and tracked the results over six months. That’s the split worth copying: automate the long tail, hand-polish the money pages.
AI-generated alt text isn’t perfect out of the box, though. It can be vague or generic, labeling something “a person” instead of “a nurse assisting a patient”, so a quick human pass still matters, especially on branded or high-traffic images. Run the bulk pass, then spend an afternoon fixing the descriptions that clearly missed the mark: wrong color, wrong material, or too generic to mean anything.
One more thing worth flagging: structured data and captions work alongside alt text, not instead of it. Schema markup lets you tag product images with metadata search engines can use for rich results, and captions, which people actually read more than body copy, add another layer of context. None of these replace alt text. They stack on top of it.
What to Do Now
Pick your top 20 product pages. Open each image, check the alt text, and rewrite anything that’s empty, a filename, or a single lazy word. That’s maybe an hour of work for most stores, and it’s the highest-leverage hour you’ll spend on image SEO this month.
Once that’s done and you’re ready to tackle the rest of your catalog at scale, that’s where automation earns its keep, same logic as building out your broader automation stack instead of doing repetitive SEO work by hand forever.