Social media specs

The real limits for posting on every major social and ad platform. Caption and post lengths counted the way each platform counts (X weighting, Bluesky graphemes plus bytes, Threads emoji bytes, TikTok video vs photo), image and video sizes and aspect ratios per placement, file and duration caps, and the safe zones where app buttons cover a vertical video. Use before writing a caption, exporting a creative or scheduling a post.

Use this before you write a caption, export an image or video, or schedule a post. Every number here comes from the platform's own documentation; the full dataset with a source link per row, a counting library and a CLI is social-media-specs.

If Node is available, check instead of counting by eye:

bash

npx social-media-specs fit "<caption>"                              # every channel at once
npx social-media-specs media instagram-reel 1080x1920 --video --seconds 40
npx social-media-specs ad meta.primary-text "<ad text>"

Post text

Channel	Limit	How it counts
X	280 (25,000 with X Premium)	Links count 23; CJK characters and every emoji count 2
Threads	500, max 5 links	Each emoji counts as its UTF-8 bytes (about 4)
Instagram caption	2,200, max 30 hashtags, 20 @mentions
Facebook post	63,206
LinkedIn post	3,000	Over-length is refused, not cut
Pinterest	title 100, description 800
YouTube	title 100, description 5,000 bytes, tags 500 combined	A tag with a space costs 2 extra
TikTok	video caption 2,200; photo post title 90, caption 4,000	Swapping photo for video can break the caption
Bluesky	300 graphemes and 3,000 bytes	Both apply
Telegram	4,096; 1,024 once media is attached
Google Business Profile	1,500

What matters more than the cap: the feed shows only the first one to three lines. Put the point in the first line.

Image and video sizes

Placement	Export at	Shape	Notes
Instagram post (app)	1080 x 1440	3:4 (accepts 3:4 to 1.91:1)	Grid tiles are 3:4
Instagram post (API or scheduler)	1080 x 1350	4:5 to 1.91:1	3:4 is refused; JPEG, 8 MB
Instagram Story / Reel	1080 x 1920	9:16	Reels: 720 px minimum, 30 fps
Meta feed ad	1440 x 1800	4:5	30 MB image, 4 GB video
Meta Story / Reels ad	1440 x 2560	9:16	Keep 14% top, 35% bottom, 6% sides clear
TikTok video	1080 x 1920	9:16
TikTok In-Feed ad	1080 x 1920	9:16, 16:9 or 1:1	540 x 960 minimum, 500 MB, 10 min
YouTube video	1920 x 1080 or 3840 x 2160	16:9
YouTube Short	1080 x 1920	9:16 or square	Up to 3 minutes
YouTube thumbnail	3840 x 2160	16:9	640 wide minimum; 2 MB from a phone
YouTube banner	2560 x 1440	16:9	Text inside the centre 1235 x 338 (at 2048 x 1152)
LinkedIn image	1080 x 1350	4:5 to 3:1	552 x 276 minimum, 5 MB
X image	1080 x 1080	1:1, 4:5, 2:3, 16:9, 9:16, 1.91:1	5 MB, GIF 15 MB
Pinterest Pin	1000 x 1500	2:3	Taller may be cut off

Safe zones on vertical video

On a 9:16 frame, the apps cover roughly the top 8 to 9%, the bottom 9 to 14%, a column of buttons on the right 18 to 22% (from about 40% down), and the caption block above the bottom bar. Keep text, faces, logos and the product in the centre-left area. For Meta Story and Reels ads, Meta's own guidance is 14% top, 35% bottom and 6% on each side.

Before you post

• Caption fits the strictest channel you are posting to (check X and Bluesky first; they are the tightest)
• The first line carries the point
• Media is exported at the placement's size and shape, not cropped by the platform
• Nothing important sits in a safe-zone band
• Video is within the duration and file limits