Type once, see what fits everywhere. Live limits for X, Threads, Instagram, TikTok, LinkedIn, Facebook and YouTube Shorts. Free, no signup, nothing leaves your browser.
Writing one caption for 8 platforms by hand gets old. Smart Post Studio's AI Writing Studio drafts platform-aware captions (Instagram length ≠ X length) and schedules everywhere from your desktop — free plan, no card.
Try the free planNotes on how platforms count. Limits above are the published caps as of September 2026. X counts every URL as 23 characters regardless of its real length, and paid X tiers allow up to 25,000 characters. Threads allows a separate 10,000-character text attachment beyond the 500-character post. Instagram shows roughly the first 125 caption characters before "…more"; TikTok truncates around 100–150 characters in the feed. This counter uses Unicode code points, which can differ by a character or two from a platform's own counter on emoji-heavy text. Fanvue has no publicly documented caption limit, so it isn't scored here.
More free tools: smartpoststudio.com/tools