The Threads character limit is 500 characters for a standard post, reply, or quote. A separate text attachment, rolled out in September 2025, holds up to 10,000 characters that don't count against that 500-character cap, and the bio is capped at 150 characters. Here's exactly what counts toward each limit, what Meta's own developer documentation says about the text attachment, and why most schedulers, Synapse included, still can't publish one through it.
Threads character limits at a glance
| Surface | Limit | Notes |
|---|---|---|
| Post, reply, or quote | 500 characters | Same cap across all three, per Meta's Threads API |
| Bio | 150 characters | Mirrors your linked Instagram bio, not set separately |
| Text attachment | 10,000 characters | Launched September 2025; a separate field, not counted toward the 500-character post cap |
| Unique links per post | 5 links | New API limit effective 22 December 2025; posts over it fail to publish |
What counts toward the 500-character limit
Most emoji count as more than one character against the 500-character limit. Threads measures length in Unicode code units rather than visual characters, and many emoji (especially flag and family emoji) weigh two or more characters each, according to typecount.com's character-limit breakdown, which it dates as last verified in August 2026. Whether a link in the main post counts toward those 500 characters is murkier: unlike X, which shortens every link to a fixed 23 characters through its own t.co service, Threads has no equivalent shortener, and sources disagree on whether a URL counts at its full length or not at all. If a draft is close to the cap, run it through a character counter instead of estimating by eye, especially if it's emoji-heavy.
The 10,000-character text attachment, and why it isn't a longer post
Meta's developer documentation lays out the mechanics: a text attachment is a separate object you send when creating a post, with a plaintext field capped at 10,000 characters, plus optional text styling (bold, italic, highlight, underline, strikethrough) and an optional link, per Meta's Threads API reference. It isn't an extension of the main post's 500-character field; it's a second block that opens full-screen when a reader taps it, and only a text-only post with no poll is eligible for one. Engadget reported the feature launched for everyone, not a paid tier the way X gates its own long-form posts, on 4 September 2025.
Can a scheduler actually post a text attachment?
Not through the standard posting flow most tools use. Threads' create-post endpoint caps the main text field at 500 characters regardless of what's attached, and Meta's own API notes rule out a text attachment on any post that already carries a poll or a conflicting link attachment. Synapse's own Threads integration posts through that standard 500-character field today, the same as most dedicated Threads schedulers — it doesn't yet expose the separate text-attachment flow, so a post that needs the full 10,000 characters still has to be composed by hand in the Threads app itself. It's a narrower version of a pattern covered in how often to post on Threads: native features tend to ship well before the scheduling layer catches up to them.
Working around the cap without a text attachment
Until a scheduler supports the text-attachment flow, the practical workaround is the one creators used before September 2025 existed at all: split a long thought into a reply chain. Each reply gets its own 500-character budget, and Threads displays the original poster's own replies nested under the parent post, so a three-part reply chain effectively stretches the usable length to 1,500 characters without touching the attachment feature. The tradeoff is that a reply chain isn't one shareable unit the way a text attachment is. Anyone who reposts the first part doesn't automatically carry the rest of the chain with it, and a scheduler that queues a thread has to publish each reply in order, immediately after the one before it, rather than treating the whole chain as a single post.
What is the character limit for a Threads post?
500 characters for a standard post, and the same 500-character cap applies to replies and quote posts.
Does a link count toward the 500-character limit on Threads?
Sources disagree. Threads has no link-shortening system like X's t.co, and whether a URL counts at its full length or not at all isn't settled by Meta's own documentation, so test a link-heavy draft before relying on either claim.
Is the Threads bio the same as my Instagram bio?
Yes. Threads shares your bio directly from the linked Instagram profile, so editing one changes the other, and both are capped at 150 characters.
Can I schedule a Threads text attachment with a tool?
Not with most schedulers today, Synapse included. The posting flow caps the standard text field at 500 characters regardless of the attachment, so a full 10,000-character text attachment still has to be posted by hand in the Threads app.
How many links can one Threads post include?
Up to 5 unique links as of 22 December 2025. Meta's API rejects a post over that limit with a THREADS_API__LINK_LIMIT_EXCEEDED error.
Do emoji count as one character on Threads?
Usually not. Threads measures length in Unicode code units, and most emoji take up two or more characters of the 500-character budget, with flag and family emoji costing even more.