Character limits vary more than most people expect, from X’s tight 280 characters to Reddit’s 40,000-character self-posts. Some platforms cap the whole post as one field, others split it into a title and a body, or a message and a caption, each with its own separate limit. Knowing which field you’re actually filling in matters as much as the number itself.
Summary table
| Platform | Limit | Notes |
|---|---|---|
| X (Twitter) | 280 characters | Shortest of the major platforms |
| Bluesky | 300 characters | Slightly more room than X |
| Threads | 500 characters | Same cap as Mastodon |
| Mastodon | 500 characters | Can vary slightly by server |
| 500 characters | Pin description | |
| Google Business Profile | 1,500 characters | Post content |
| 2,200 characters | Caption, only ~125 shown before the fold | |
| TikTok | 2,200 characters | Caption |
| Discord | 2,000 characters | Per message, splits automatically for more |
| 3,000 characters | Post content | |
| Telegram | 4,096 characters | Text message; captions on media are 1,024 |
| YouTube | 5,000 characters | Video description |
| Tumblr | 4,096 characters per block | No practical ceiling on total post length |
| 63,206 characters | Rarely a real constraint | |
| 40,000 characters | Self-post body; title is capped at 300 |
For the full breakdown on any one platform, including bio limits, comment limits, and platform-specific quirks, see the dedicated posts: X, Threads, Bluesky, Mastodon, Instagram, TikTok, Facebook, LinkedIn, Pinterest, YouTube, Google Business Profile, Reddit, Discord, Telegram, Tumblr, and Snapchat.
What actually counts toward the limit
Links, line breaks, emoji, and mentions all count as characters on most platforms, the same as any other text. A long URL can eat a noticeable chunk of a 280-character X post before you’ve written a word of your own. Some platforms shorten links automatically for display while still counting the full URL against the limit internally, so what you see on screen isn’t always what’s being measured.
Hashtags count too, on every platform that supports them. A caption padded with 20 hashtags is spending real characters that could otherwise go toward the caption itself.
Writing for the fold, not just the limit
On most platforms, the character limit and the amount actually visible before someone has to tap or click are two very different numbers. Instagram allows 2,200 characters but shows roughly 125 before the “more” link. LinkedIn and Facebook both fold long posts behind a “see more.” The limit tells you the ceiling, it doesn’t tell you what gets read.
Write the first line as if it’s the whole post, because for a large share of your audience, it effectively is. Everything after the fold is for the people who already decided to stay.