Threads Guide: Formats, Limits and Best Practices

500 characters, 20-item carousels, text attachments, topic tags and links: how to show up on Threads as a brand.

Published on September 23, 2026 · Social platforms

Threads is Meta's conversation network, built on top of Instagram. You can post short text, images, video, and more recently long-form text as an attachment. For a brand it's a place where voice matters more than visuals: a clear opinion, a well-framed question or a concrete tip travels further there than anything that reads like an ad. This guide covers the technical limits we verified in Meta's official documentation, what Meta says about how the feed works, and a practical way to show up consistently.

Formats and limits

The numbers below come from Meta's Threads API documentation. They apply to publishing through a tool and largely match what the app allows.

Text: 500 characters

A 500-character cap forces tight writing. Meta notes that emojis are counted by their UTF-8 byte size, so a single emoji can eat several characters of your budget. If your message won't fit, you have two options: split it into a chain of posts, or use a text attachment.

Text attachments: up to 10,000 characters

Announced by Meta in September 2025, text attachments let you add a long piece of up to 10,000 characters, per the dedicated documentation, with basic styling: bold, italic, highlight, underline and strikethrough. They only work on text posts, with no image, video or poll. It's the right format for a lessons-learned post, a mini guide or a reasoned point of view, without sending readers off the app.

Carousels and video

A Threads carousel takes 2 to 20 items, images and video mixed. Videos can run up to 5 minutes. On Threads, the image supports the point rather than carrying it: an annotated screenshot, a product photo in context, a readable diagram. Aspect ratios are very flexible (up to 10:1), but vertical or square visuals are still the easiest to read in a mobile feed.

Links

A post can contain at most 5 links, attachment included. Since December 2025, the API rejects posts with more. In practice one link per post is almost always enough, and the text should deliver the substance on its own. The link is a bonus, not the only reason the post exists.

Topic tags

Threads doesn't use hashtags the way Instagram does. Each post can be attached to a topic between 1 and 50 characters long, and Instagram's Help Center states that a post can carry only one topic. Choose it carefully: it's how Threads understands what you're talking about and who might care.

How Threads decides what to show

Meta publishes an explanation of Threads feed ranking in its Transparency Center. The gist: the For You feed draws on how each person has interacted with similar accounts, content and interests to surface what they're most likely to find valuable. There's also a Following feed in chronological order for people who only want to see accounts they follow.

Meta doesn't publish a precise, weighted list of signals. Rather than chasing a hack, take what follows from the principle: a post that sparks replies and conversation among people interested in your topic is more likely to be shown to others like them. Threads is a network of replies. A brand that posts and never replies stays invisible.

What a brand should post on Threads

• Short takes. A reasoned opinion on a practice in your industry, in three sentences.
• Open questions. Ask your audience about a product choice, a habit or a real-world dilemma.
• Actionable tips. Something readers can use right away without clicking anywhere.
• Behind the scenes. A workshop photo, a prototype, a mistake you fixed, with two lines of context.
• Long text attachments. For topics that deserve real depth.
• Replies. Joining conversations in your space is part of your presence, not just your own posts.

Don't paste your Instagram captions as-is. Threads is more direct and conversational, and a caption written to sit under a photo often falls flat when it has to stand alone.

A sample week on Threads

To turn this into practice, here's what a week could look like for a brand getting started on Threads. It isn't a rule, just a framework to adjust to your industry and the time you actually have.

• Monday: an open question tied to your line of work, such as the first thing customers look at before they buy. Reply to every answer the same day.
• Wednesday: a concrete tip in under 500 characters, with a photo or screenshot if it helps.
• Thursday: a short behind-the-scenes carousel: production, packing an order, setting up a booth.
• Friday: a text post with a long attachment that goes deep on one topic, for example the three mistakes you see customers make most often and how to avoid them.

Between those posts, a few minutes a day spent replying and commenting on posts in your space often does more for your visibility than one more post would.

Threads and Instagram: a useful link

A Threads profile is tied to an Instagram account, so your Instagram followers can find you easily, which helps you get started. But the link doesn't mean both audiences want the same thing. People come to Instagram to look; they come to Threads to read and reply. Keep the same brand identity, not the same copy.

Writing for a 500-character post

Short doesn't mean shallow. The posts that work best in a tight format usually follow a simple shape: a first line that states the idea plainly, one or two sentences of evidence or example, and a closing line that invites a reply. Cut adjectives before you cut substance, and drop anything the reader could guess. If you still need more room, that's your signal to move the depth into a text attachment instead of cramming it in.

How often to post

Meta doesn't recommend a specific frequency. Because Threads runs on conversation, steady presence matters more than an occasional polished post. A reasonable baseline for a brand: a few short posts a week, plus time set aside to answer replies and comment on posts in your industry. On the technical side, the API limit of 250 posts per profile per 24 hours sits far above any normal editorial use.

Common mistakes

1. Going over 500 characters. Depending on the tool, the post gets rejected or cut. Count emojis, which weigh more.
2. Stacking links. More than 5 and the post fails. And a post that's just a link rarely gets replies.
3. Pasting a wall of hashtags. Threads works with one topic per post, not a hashtag list.
4. Adding a long text attachment to a post with an image. Text attachments only work on text-only posts.
5. Posting without replying. Conversation is the core of the network. Ignoring it means talking to yourself.
6. Recycling other networks word for word. The same message lands better rewritten for a conversational format.

Pre-publish checklist

• Text at 500 characters or less, emojis included.
• One idea per post, stated in the first sentence.
• A topic tag that is specific and relevant.
• 5 links at most, ideally one.
• Carousel of 2 to 20 items if you illustrate, video up to 5 minutes.
• Text attachment only on media-free posts, 10,000 characters max.
• Time blocked to reply in the hours after posting.

Keeping pace on Threads and everywhere else

Threads needs a consistent voice and short messages tailored to each topic, on top of everything your other networks already demand. With Oposto, you describe your brand once: it learns your voice, products and audience from your website, adapts each post to each network, including Threads' 500-character limit, plans it in a calendar and publishes it at the scheduled time. Then it measures real performance and reuses what works.

To see next month's posts ready for review, try Oposto: describe your brand once, it prepares a month of content in the right format for each network, and you approve.