Does Custom Instagram Alt Text Improve Reach?


Social SEO is a hot topic at the moment; Instagram alt text may be trending even harder than ChatGPT. And while there’s a ton of content explaining theoretical best practices, there aren’t a lot of blogs that show someone actually testing it out.

Here at Hootsuite, we pride ourselves on practicing what the thought-leaders preach, showing instead of telling, and getting our dainty, digital hands in the theoretical mud. We’re social media scientists! We test theories when we see ‘em!

And today, we’ve got an experiment for you. Join us in testing whether writing custom alt text on Instagram can boost reach.

Hypothesis: Writing custom Instagram alt text will get my posts more reach

Let’s get one thing out of the way: Instagram alt text is a must for all marketers. Accessibility is important, and inclusive design opens up your content to visually impaired audiences.

But what if alt text can also improve your social SEO?

For anyone new here, alt text is the additional descriptive copy used to describe the contents of an image within HTML code. It makes your content accessible to people who use screen readers and can increase your chances of appearing in searches.

Instagram offers AI-generated automatic alt text, but you can also write your own.

We want to know if custom Instagram alt text could be a new weapon in your arsenal for battling the wastelands that are Instagram SEO. Or, just you know, boost the numbers in your analytics a little.

Today’s hypothesis is that custom alt text will earn us more reach than relying on Instagram’s auto-generated alt text.

Let’s see which text will prevail!


To test the alt text theory, I pulled up my Hootsuite dashboard and scheduled six different posts.

Three have original, custom alt text, and three have Instagram-generated alt text.

I tried to keep the content as similar as possible to avoid bias. For this experiment, I chose to post book reviews because it’s my love language, and Instagram has a robust #bookstagram community.

I also let Hootsuite decide on the best times to post (with each post a few days apart) to encourage engagement.

Now, my personal Instagram account has a whopping 801 followers, so I was expecting some juicy results.

create new Instagram post using Hootsuite

I published the first post (on the book Tender is the Flesh) with Instagram’s default alt text. Then, I alternated posts featuring custom alt text with posts featuring default alt text over the next week.

The schedule was as follows:

Name Type Schedule
Tender is the Flesh Default alt text Published Wednesday, 12 PM
Young Mungo Custom alt text Published Friday, 9 AM
I’m Glad My Mom Died Default alt text Published Monday, 11 AM
Know My Name Custom alt text Published Wednesday, 12 PM
Black Leopard, Red Wolf Default alt text Published Friday, 9 AM
Sex Cult Nun Custom alt text Published Monday, 11 AM

Each book was reviewed in a similar caption length (no spoilers, of course), and I included the same hashtags (#bookstagram and #goodreads).

Default alt text…

The default alt text for the first photo is simply “Photo by Colleen Christison on February 22, 2023. May be an image of book.” The rest of the default alt text is similarly written.

…vs custom alt text

I wrote a much more detailed, keyword-rich image description for the custom alt text.

For Young Mungo, for example, I wrote, “The image depicts a book lying flat on a peach-colored felt background. The book is Young Mungo by Douglas Stuart.

“You can only see the cover of the book, not the pages, which state the title ‘Young Mungo’ across the top of the book in a large, white typeface. The bottom of the book, in the same white but slightly smaller typeface, reads, ‘Douglas Stuart.’ Then, underneath that, in an even smaller typeface, it reads, ‘Booker prize-winning author of Shuggie Bain.’

“The image on the book’s cover is of a caucasian teenage boy with his mouth and nose underwater. He has delicate features and full lips. You cannot see the boy’s eyes, only the lower half of his face and his right shoulder. He is lit up by the sun shining through the water. The sun is refracted through the water’s surface, making patterns of light across the boy’s face and shoulder.”

Then, I rinsed and repeated this strategy for the other posts.


The results are in! As you can see, there were two runaway stars of the show: I’m Glad My Mom Died and Sex Cult Nun. (Two of the spiciest titles of the bunch.)

Name Type Results
Tender is the Flesh Default alt text Reach: 273

1 non-follower

Impressions: 324

1 of which was from the Explore page

Post Interactions: 28

1 Save

Young Mungo Custom alt text Reach: 273

1 non-follower

Impressions: 316

Post Interactions:

1 Save

I’m Glad My Mom Died Default alt text Reach: 451

6 non-followers

Impressions: 493

3 were reached from hashtags
3 were reached from Other

Post Interactions: 46

3 Saves

Know My Name Custom alt text Reach: 239

6 non-followers

Impressions: 264

4 were reached from hashtags
2 were reached from Other

Post Interactions:

0 Saves

Black Leopard, Red Wolf Default alt text Reach: 227

2 non-followers

Impressions: 249

3 were reached from Other
1 was reached from Explore

Post Interactions:

2 Saves

Sex Cult Nun Custom alt text Reach: 342

1 non-follower

Impressions: 360

1 was reached from hashtags

Post Interactions:

0 Saves

Here are the reach results from this experiment in Instagram’s own analytics.

instagram content photos of books with impressions


Bonus: I also increased my overall followers by a whopping 1.7%.

What do the results mean?

Alright, so we’ve got our numbers. But what do they really mean?

The TL;DR of it is that the numbers don’t tell us (without a shadow of a doubt) whether or not custom alt text performs better than default alt text.

The experiment was inconclusive…

Unfortunately, the results were fairly similar, with one stand-out piece of content: The book review of Jenette McCurdy’s I’m Glad My Mom Died. This could be due to a few factors. It could be because the book was trending last year (due to her shocking title) or more of a “right time, right place” situation.

The post that came in second, Sex Cult Nun, also has a shocking title and was posted at the same time as the first-place post, Monday at 11 AM. Hmm.

The first-place post had default alt text, while the second-place post had custom alt text.

To test the theories of success further, I could review other books that were trending in 2022, others with shocking titles, or try to post again on Mondays at 11 AM and see how my content performed. I would continue to alternate custom alt text with default alt text until I saw patterns emerge.

It would take further a/b testing to find out just why these two posts were in the top place.

…but that doesn’t mean you shouldn’t write your own alt text

The benefits of alt text go far beyond reach and engagement rates on Instagram. Alt text allows your content to be consumed by the visually impaired, creating a more equal experience across social media.

Plus, including folks in this demographic in your content strategy opens up your potential reach to a wider audience. Be inclusive on social media; it’s the cool thing to do.

Hashtags are still relevant

You can see from the results that users still find content to engage with via hashtags. Keep up the good hashtagging work!

There are a few disclaimers we need to make

There are a couple factors we need to keep in mind when considering these results.

The first is that my last Instagram post was from September of the previous year. The more active your account is, the more likely people will engage with your content. And the more likely Instagram is to share your content on their discovery feed. So, this was a bit of an uphill battle in the beginning, which could have affected the results.

Psst: Don’t be like me. Schedule your posts in advance with Hootsuite and stay relevant, engaged, and on top of your content.

Also, my captions were pretty long, as I was using them to review the books I posted. The ideal caption length for Instagram is 138 to 150 characters, so I went a bit overboard with my zealous book reviews. In the future, I’ll be experimenting with caption length.

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