Social Media Image Sizes and Specs (2026)
Post sizes, video aspect ratios, and caption limits for every network PostQuest publishes to. Each value comes from the rules PostQuest uses to check posts before they go out.
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Post sizes and caption limits by network
| Network | Main post size | Video aspect ratio | Caption limit |
|---|---|---|---|
| 320–1,440 px wide · 4:5 to 1.91:1 · Up to 8 MBPhoto Post | 9:16 recommendedReel | 2,200 characters | |
| Up to 10 MBImage Post | 9:16Video Story | 5,000 characters | |
| X | < 10:1 · Up to 5 MBImage Post | 1:3 to 3:1Video Post | 280 characters |
| YouTube | At least 2 s · Up to 4 GBVideo | 9:16 or 1:1Short | 5,000 characters |
| TikTok | 360–4,096 px per side · 3 s–10 min · Up to 4 GBVideo | Not specified | 2,200 characters |
| 2:3 recommended · Up to 10 MBImage Pin | 1:1, 2:3, 4:5, or 9:16Video Pin | 800 characters | |
| Up to 8 MBPhoto Post | 9:16 to 16:9Video Post | 3,000 characters | |
| Threads | 360–1,440 px wide · Under 10:1 · Up to 8 MBPhoto Post | 0.01:1 to 10:1; 9:16 recommendedVideo Post | 500 characters |
| Bluesky | Up to 1 MBPhoto Post | Not specified | 300 graphemes |
| Mastodon | Up to 16 MB (instance default)Photo Post | Not specified | 500 characters (instance default) |
Open a network for every content type, file and video limit, hashtag rule, and profile image size.
Specs by network
Social media specs FAQ
Which social network has the shortest caption limit?
X has the shortest caption limit at 280 characters on a free account. Facebook and YouTube allow the longest captions at 5,000 characters.
Which networks accept 9:16 vertical video?
Instagram, Facebook, X, YouTube, Pinterest, LinkedIn, and Threads accept or recommend 9:16 video for at least one format. Check each network page for the exact format and length limits.
Where do these specs come from?
Publishing limits come from the capability rules PostQuest uses to validate posts, checked against each network’s official API documentation on September 11, 2026. Profile and banner sizes come from each network’s help center or docs.
Schedule posts that pass these checks
PostQuest validates every caption and file against these limits before a post is scheduled, so nothing fails at publish time.