Quick Answer: What Are the Character Limits on Each Platform?
X allows 280 characters (25,000 on Premium), Threads 500, Bluesky 300, Instagram and TikTok 2,200, LinkedIn 3,000, YouTube descriptions 5,000 with a 100-character title, Reddit titles 300 with a 40,000-character body, and Facebook 63,206 — though Facebook engagement drops sharply after about 500. Three of those numbers are not counted the way you would expect: X counts every link as 23 characters and emoji or CJK text as 2, and Bluesky counts graphemes rather than characters.
These are the limits Autoadify enforces when it publishes, reviewed against each platform's developer documentation in September 2026. Where sources disagree, we say so rather than pick a number.
Character limits by platform
| Platform | Post text | Title / headline | Counting rule worth knowing |
|---|---|---|---|
| X (Twitter) | 280 (25,000 on Premium) | — | Links count as 23. Emoji and CJK characters count as 2 |
| Threads | 500 | — | Counted as written |
| Bluesky | 300 | — | Graphemes, not characters: a family emoji is 1, not 11 |
| 2,200 | — | Maximum 30 hashtags | |
| TikTok | 2,200 | — | Caption on a video or photo post |
| 3,000 | Articles: 100 | Certain symbols must be escaped through the API, or the post is cut short | |
| YouTube | 5,000 (description) | 100, required | Up to 15 hashtags |
| 40,000 (body, optional) | 300, required | The title carries the post; each subreddit adds its own rules | |
| 63,206 | — | Engagement falls away after roughly 500 |
The counting rules that break posts under the limit
Most "post failed" surprises are not about length. They are about how the platform counts.
- X weights characters. Latin text counts one per character, but emoji, Chinese, Japanese and Korean count two. A 140-character Japanese post is already at the limit. Every URL counts as exactly 23, so a short link saves you nothing and a long one costs you nothing.
- Bluesky counts graphemes. A grapheme is what a reader sees as one character. A flag or a family emoji is several code points but one grapheme, so Bluesky is more generous with emoji than a naive counter suggests — and a tool that counts with a plain string length will reject posts Bluesky would accept.
- LinkedIn's API parses symbols. Brackets, parentheses, asterisks, underscores and a handful of others open formatting elements. Sent unescaped through the API, the first one can silently cut off the rest of your post. We wrote up the LinkedIn parenthesis problem separately because it returns success while publishing half a post.
Image sizes and how many images each post takes
| Platform | Best ratio | Export size | Images per post | Notes |
|---|---|---|---|---|
| 4:5 | 1080 × 1350 | 1, or 2–20 as a carousel | Every carousel slide must share one ratio. The grid crops to 3:4, so keep the subject centred | |
| 4:5 (posts), 1:1 (carousels) | 1080 × 1350 / 1200 × 1200 | Up to 10 | Mixed ratios in a carousel are letterboxed | |
| 1.91:1 | 1200 × 630 | Up to 9 | Square and 4:5 also work. A PDF posts as a swipeable document | |
| X | 16:9 | 1920 × 1080 | Up to 4 | 5 MB per image |
| Threads | 1:1 | 1080 × 1080 | Up to 20 | 4:5 and 16:9 also work |
| Bluesky | 1:1 | 1080 × 1080 | Up to 4 | 1 MB per image — larger files are rejected, not resized |
| TikTok | 9:16 | 1080 × 1920 | Up to 35 (photo post) | Photo posts play with a soundtrack |
| 1:1 | 1080 × 1080 | 1 (image post) | 20 MB per image | |
| YouTube | 16:9 (thumbnail) | 1280 × 720 | — | Thumbnails are capped at 2 MB and must read at about 200 px wide |
Video length limits
| Platform and format | Maximum | Recommended | Ratio |
|---|---|---|---|
| TikTok | 10 minutes | Under 60 seconds | 9:16 |
| Instagram Reels | Disputed (see below) | Under 3 minutes | 9:16 |
| Instagram and Facebook Stories | 60 seconds | — | 9:16 |
| Facebook Reels | 3 minutes | 90 seconds if you plan to boost it | 9:16 |
| YouTube Shorts | 3 minutes | — | 9:16 |
| YouTube (long-form) | 12 hours on a verified channel | — | 16:9 |
| X | 140 seconds (longer on Premium) | — | 16:9, 1:1 or 9:16 |
| 10 minutes | — | 1:1 or 16:9 | |
| Threads | 5 minutes | — | 9:16 or 1:1 |
Two of these are genuinely contested. Instagram's hard Reel cap is reported as 90 seconds, 3 minutes or 15 minutes depending on how the video is uploaded; what is not disputed is that Instagram stops recommending Reels longer than 3 minutes to non-followers, which is the number that matters. YouTube Shorts moved to 3 minutes, but some sources still quote 60 seconds. One more trap on X: H.265 (HEVC) video is rejected. Many phones export H.265 by default, so re-encode to H.264 first.
Platforms that will not publish text on its own
- Instagram has no text-only post type. Every post needs an image or video.
- TikTok publishes only videos and photo posts.
- YouTube publishes only video. A still image will not post, and Community posts have no public API, so they cannot be scheduled from any third-party tool.
If you schedule one caption to every network, these three are where it fails. Check before you schedule rather than at publish time, when nobody is watching.
Account rules that matter as much as the limits
- Instagram publishes through the API only from Business or Creator accounts, not personal ones.
- Facebook publishes to Pages only. No API can post to a personal profile.
- TikTok requires the creator to choose the privacy level and the comment, duet and stitch settings for each post. A tool may not choose for you.
- YouTube forces every upload to private when the posting app has not passed Google's audit, whatever privacy you asked for.
- Reddit needs a target subreddit for every post, and each subreddit sets its own rules on flair and self-promotion.
Things you can generate but not publish through an API
X Articles, LinkedIn articles and newsletters, and YouTube Community posts have no publishing API. Any tool that claims to schedule them is either posting something else or asking you to paste it in yourself. Autoadify can write them; you publish them by hand.
Frequently Asked Questions
What is the character limit on X in 2026?
280 characters for standard accounts and 25,000 for Premium. Links always count as 23 characters, and emoji and CJK characters count as 2.
What is the Threads character limit?
500 characters per post, with up to 20 images or one video of up to 5 minutes.
What is the Bluesky character limit?
300 graphemes. A grapheme is one visible character, so an emoji made of several code points still counts as one.
What size should Instagram images be?
1080 × 1350 pixels at 4:5. It fills the most of the feed, and it survives the profile grid's 3:4 crop better than a square does.
How long can a TikTok be?
Up to 10 minutes, but short videos under about 60 seconds remain the safer choice for reach.
Why did my LinkedIn post get cut off?
If it was published through the API, an unescaped symbol such as a parenthesis probably truncated it. LinkedIn returns success either way. Here is how to fix it.
Can I post the same caption to every platform?
You can, but it will be truncated on Bluesky and X, rejected on Instagram, TikTok and YouTube without media, and lost below the fold on Facebook. Per-platform versions of the same post do much better. Our guide to cross-posting properly covers how.
The Bottom Line
Write to the shortest limit you are posting to, export images at the platform's preferred ratio, keep videos inside the recommended length rather than the maximum, and attach media wherever a platform requires it. Most failed posts come from counting rules and missing media, not from going over a number.
Let the limits check themselves
Autoadify applies every rule on this page at the moment you write, not at the moment a post fails: it checks each platform's limits as you write, flags missing media before you schedule, and resizes images for Bluesky's 1 MB cap. Start free and connect the networks you post to.
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