Instagram Reels, TikTok, and YouTube Shorts have converged on similar target specs - vertical 9:16 aspect ratio, MP4 or MOV container, H.264 or HEVC video, AAC audio - but each platform is picky in different ways at the edges. Uploading a file that misses the spec triggers server-side re-compression that stacks visible quality loss on top of any compression you already did. Here's the current spec sheet for each and the prep that avoids the re-compression penalty.

#Instagram Reels (2026 specs)

  • Aspect ratio: 9:16 (vertical). 4:5 also accepted for feed posts but not Reels tab.
  • Resolution: Upload at exactly 1080x1920. Instagram has historically displayed video at up to 1080 pixels wide, so anything larger just gets resized by Instagram itself.
  • Duration: Up to 3 minutes (raised from 90 seconds in January 2025).
  • Container: MP4 preferred; MOV accepted. Instagram converts on upload regardless.
  • Video codec: H.264 or HEVC. Both are accepted; iPhone HEVC clips uploaded straight from the phone are fine, and H.264 is the safest choice for files prepared on a computer.
  • Audio codec: AAC-LC.
  • Video bitrate: No published target, and Instagram re-encodes everything. Upload with headroom - around 8-10 Mbps at 1080x1920 - so its encoder starts from a clean picture.
  • Audio bitrate: 128 kbps stereo.
  • File size: Up to 4 GB.
  • Frame rate: 23.98, 25, 30, 50, or 60 fps. Anything else gets converted.

#TikTok (2026 specs)

  • Aspect ratio: 9:16 preferred; 16:9 supported (but presented in a smaller player).
  • Resolution: Recommended 1080x1920. Up to 4096x4096 accepted; TikTok downscales.
  • Duration: 3 seconds to 10 minutes (raised from 3 minutes in 2022). Longer durations exist in some regions but 10 minutes is the reliable cap.
  • Container: MP4 or MOV.
  • Video codec: H.264 or HEVC.
  • Audio codec: AAC-LC.
  • Video bitrate: Up to 12 Mbps (TikTok keeps the source at this bitrate when the upload is clean).
  • File size: Up to 287 MB from mobile app, up to 1 GB from web upload.
  • Frame rate: 23.98 to 60 fps.

#YouTube Shorts (2026 specs)

  • Aspect ratio: 9:16 required. Horizontal videos get pillarboxed but lose the Shorts algorithmic push.
  • Resolution: Recommended 1080x1920. YouTube accepts up to 8K but Shorts caps at 1080p playback.
  • Duration: Up to 3 minutes (raised from 60 seconds in October 2024). Anything longer becomes a regular video, not a Short.
  • Container: MP4, MOV, WebM, MKV all accepted; MP4 recommended.
  • Video codec: H.264 recommended. HEVC and AV1 accepted (YouTube re-encodes to VP9 for delivery regardless).
  • Audio codec: AAC preferred; Opus accepted.
  • Video bitrate: No specific target; upload at source quality. YouTube re-encodes to VP9 at delivery time.
  • File size: Up to 256 GB (regular YouTube limit).
  • Frame rate: 24, 25, 30, 48, 50, or 60 fps.

#Where each platform re-compresses (and how to avoid it)

  • Instagram Reels: Aggressive re-compression on every upload, and no file format avoids it. The best you can do is give it a clean starting point: exactly 1080x1920, H.264, around 8-10 Mbps, and the Upload at highest quality setting turned on in the app (with it off, the app can shrink your video before it uploads). Compress video for Instagram walks through each step, including cropping landscape footage to 9:16.
  • TikTok: Less aggressive re-compression than Instagram. A clean 1080x1920 H.264 or HEVC upload at 8-12 Mbps is retained close to source quality. The web upload path preserves more bitrate than the mobile app upload path.
  • YouTube Shorts: Least aggressive re-compression - YouTube keeps high source quality and re-encodes to VP9 for delivery only. Upload at maximum quality (or your device's native output).

#Format prep before upload

  1. Aspect ratio must be 9:16. A horizontal camera capture (16:9) doesn't become a Reel by getting uploaded - it becomes a pillarboxed clip with wasted screen space and dies in the algorithm. Shoot vertical or crop/re-frame in an editor first. iOS Photos → Edit → Crop → 9:16 works for iPhone captures.
  2. Container must be MP4 or MOV. WebM and MKV work only on YouTube Shorts. Convert other containers first with the relevant Wave page.
  3. iPhone Screen Recording captures are MOV. Instagram and TikTok both accept MOV straight from the phone. Converting via iPhone screen recording to MP4 helps when the file is going somewhere else first - a computer, an editor, or an upload form that only takes MP4.
  4. GoPro captures are MP4 with the moov at the tail. This confuses some upload processors. Fast-start rewrite via GoPro to MP4 fixes the container structure for cleaner upload processing.
  5. Duration must match the platform. Reels and Shorts both take up to 3 minutes; TikTok is more generous. Trim before upload rather than letting the platform truncate.

#Bitrate targets when compressing before upload

  • Reels: 8-10 Mbps H.264 at 1080x1920. Instagram compresses again after upload, so start with headroom rather than squeezing the file first.
  • TikTok: 8-12 Mbps H.264 or 6-8 Mbps HEVC at 1080x1920. TikTok respects source quality up to about this.
  • Shorts: 12+ Mbps H.264 or 8 Mbps HEVC at 1080x1920. YouTube re-encodes to VP9 for delivery but preserves source quality internally.

#The takeaway

All three vertical platforms accept MP4 with H.264, AAC audio, and 9:16 aspect at 1080x1920. Reels re-compresses most aggressively; Shorts least. The most important prep step is getting the aspect ratio right - a 16:9 clip in a Reels feed is dead algorithmically. Convert MKV, WebM, and other non-phone formats to MP4 before uploading; leave phone footage at native quality. Don't over-compress before upload; the platforms will re-compress anyway and stacking pre-compression on server compression is where the visible quality drops.