What is alt text?

Also called alternative text, image description, alt tag.

Alt text is a short written description of an image, added to a post so that screen readers can describe the picture to people who are blind or have low vision.

Why it matters

Some of your customers can't see your photos, and without alt text a menu, a price list or an event poster tells them nothing. Most platforms let you add it in a few seconds. When you don't, some platforms try to describe the image automatically, and that guess is often vague or wrong. Writing your own is a small habit that makes every post usable by more people.

Example

A bakery posts a photo of its weekend menu board. Its alt text reads: "Chalkboard menu for Saturday: sourdough loaf 900, cinnamon bun 350, almond croissant 400, prices in rupees."

How to write good alt text

Imagine describing the photo to a customer over the phone. Say what matters for this post, not every detail in the frame.

  • Start with the main subject and what's happening: "Barista pouring a heart into a flat white".
  • Include any words in the image exactly, such as an offer, a date or a menu. Screen readers can't read text inside a picture.
  • Skip "image of" or "picture of". Screen readers already announce that it's an image.
  • Add colour, setting or expression only when it matters to the point of the post.
  • Keep it to a sentence or two. Longer descriptions are tiring to listen to.
  • Don't stuff it with hashtags or keywords. It's a description, not a caption.
  • In a carousel, write alt text for every image, not just the first.

Where to add alt text on each platform

Menu names change from time to time, but the option usually sits in an "advanced" or "edit" step after you add the image.

  • Instagram: when creating a post, open Advanced settings and choose Write alt text. To change it later, open the post's menu, tap Edit, then Edit alt text. Instagram creates automatic alt text if you don't add your own.
  • Facebook: Facebook generates automatic alt text when the person posting doesn't add any, and you can edit the alt text on photos you upload or post.
  • X: after attaching an image, select +Alt (Add description on the web), type the description and select Done. Descriptions can be up to 1,000 characters, and an ALT badge shows on the posted image.
  • LinkedIn: after uploading an image, select the Alt text option below it (ALT in the app), write the description and save. LinkedIn may add alt text automatically, so check what it wrote.
  • Pinterest: when creating a Pin, open More options and fill in the Alt text field. It allows up to 500 characters and works on standard and video Pins.

Common mistakes

Alt text is easy to get almost right. These are the slips that make it unhelpful.

  • Copying the caption into the alt text field. The caption is already read out; the alt text should describe the picture.
  • Leaving text-heavy graphics without alt text, so a poster or quote card is silent to a screen reader.
  • Relying on automatic alt text for anything important, such as prices, dates or product names.
  • Forgetting video. X says image descriptions can't be added to videos, so put spoken words in on-screen captions and describe key visuals in the post text.

Common questions

Does alt text help reach on social media?

Platforms don't publish that alt text changes how widely a post is shown, so treat it as an accessibility habit rather than a growth tactic. On a website, alt text also helps search engines understand your images.

How long should alt text be?

Usually one or two sentences. X allows up to 1,000 characters and Pinterest up to 500, but shorter descriptions are easier to listen to. Spend the words on what matters to the post, especially any text in the image.

Is alt text the same as a caption?

No. The caption is the visible text everyone reads with the post. Alt text is a description of the image itself, mainly heard by people using screen readers.

Sources: Instagram Help Centre: Add alt text to a photo, checked 14 October 2026; Facebook Help Centre: How automatic alt text works, checked 14 October 2026; X Help Centre: How to add image descriptions, checked 14 October 2026; LinkedIn Help: Add alternative text to images, checked 14 October 2026; Pinterest Help: Add alternative text to your Pins, checked 14 October 2026

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