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: Native 1080x1920. Reels downscale to 720x1280 for playback; upload at 1080x1920 for cleaner scaling.
  • Duration: 15 seconds to 90 seconds. Longer than 90 seconds is rejected.
  • Container: MP4 preferred; MOV accepted. Instagram converts on upload regardless.
  • Video codec: H.264 or HEVC. HEVC uploads with less re-compression penalty because Instagram's server keeps HEVC internally.
  • Audio codec: AAC-LC.
  • Video bitrate: 3.5 Mbps (Instagram's target for 1080x1920). Uploading at higher bitrates gets recompressed down to about this level anyway.
  • Audio bitrate: 128 kbps stereo.
  • File size: Up to 4 GB, though 100 MB+ triggers slow upload processing.
  • 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: 60 seconds maximum. 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 any upload. The best you can do is upload at 1080x1920 in H.264 at exactly 3.5 Mbps target - matches the internal spec, minimizes visible loss. HEVC uploads sometimes bypass the re-compression path (Instagram's server keeps them internally), which is why iPhone-native HEVC recordings often look better on Reels than transcoded H.264 versions.
  • 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). Wire quality tests show YouTube Shorts as the cleanest delivery of the three when the source is high quality.

#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 accepts MOV but re-compresses more aggressively; converting to MP4 first via iPhone screen recording to MP4 preserves quality slightly better.
  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. A 90-second clip fits Reels; a 60-second clip fits Shorts; TikTok is generous. Trim before upload rather than letting the platform truncate.

#Bitrate targets when compressing before upload

  • Reels: 3.5 Mbps H.264 or 2.5 Mbps HEVC at 1080x1920. Higher than that gets recompressed anyway.
  • 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 MOV to MP4 for slightly better Reels/TikTok upload handling; leave everything else 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.