How to use it
- Describe the post in a sentence or two: what’s in it and the one thing you want people to notice. “Six plants that survived a north-facing flat, watered every ten days” gives the model far more to work with than “plant post”.
- Pick the post type. A carousel caption can point people to swipe; a Reel caption backs up the video.
- Choose a tone, a call to action, a length and how many hashtags you want: none, 3 or 5.
- Take the caption closest to how you’d say it, swap in a detail only you know, and cut any line you wouldn’t say out loud.
Instagram’s caption rules
| What | Rule | Source |
|---|---|---|
| Caption length | 2,200 characters | Instagram API: publishing media |
| Hashtags | Up to 5 on a post or Reel, since 18 December 2025. With more, Instagram's help center says it won't post. | Instagram Help: Use hashtags @creators on Threads, 18 December 2025 |
| Hashtag characters | Letters, numbers and underscores. Spaces and symbols like $ or % don't work. | Instagram Help: Use hashtags |
| Mentions | Up to 20 @mentions in a caption | Instagram API: publishing media |
| Hashtag pages | Posts from public accounts show on the hashtag's page. Posts from private accounts don't. | Instagram Help: Use hashtags |
Checked against each platform’s own help and developer pages in October 2026.
Instagram’s developer docs still say 30 hashtags for posts published through its API. Its help center and its @creators account say 5, so 5 is the cap we enforce: extra tags at the end of a caption are removed, and a tag used as a word inside a sentence keeps the word and loses the #.
What makes a caption work
- The first line. In the feed, Instagram shows the start of a caption and folds the rest behind “more”. Write it so it makes sense on its own: the result, the surprise or the question.
- One idea. A carousel about six plants doesn’t need a paragraph on each one. It needs a reason to swipe.
- A call to action that fits the post. A question on a post people have opinions about, “save this” on a reference post, “link in bio” only when the link is worth the trip.
- Hashtags that describe the post. A tag files a public post on that tag’s page for people browsing it; it doesn’t show the post to more people by itself. The Instagram hashtag generator suggests a specific set of five.
Honest limits
The model can’t see your photo or video. A caption that describes the image is working from your description, so check every detail it mentions. It doesn’t know what has done well on your account, and we can check a caption’s length and hashtags but not how it will perform. If you post the same text elsewhere, the social post character counter shows how each network counts it.