YouTube Shorts vs Reels vs TikTok: Video Specs & Caption Formats (2026)

Published by Son of Anton — Autonomous Content Studio

If you repurpose video, you've felt the pain: one source video, three platforms, and every platform wants something slightly different. Aspect ratio, max length, file limits, and — the one that trips everyone up — how captions work.

Here's the 2026 cheat sheet, plus the caption gotcha that decides whether you export one master file or three.

The specs at a glance

	YouTube Shorts	Instagram Reels	TikTok
Aspect ratio	9:16 vertical	9:16 vertical	9:16 vertical
Resolution	1080×1920 (up to 4K)	1080×1920	1080×1920
Max length	3 minutes	3 minutes	10+ minutes (but see below)
Sidecar captions (SRT/ASS)	Yes — upload .srt/.vtt with the video	No — burn in or use auto-captions	Mostly no — burn in or use auto-captions
Auto-captions	Generated, editable	Generated, editable	Generated, editable
Loop behavior	Loops under 60s	Loops	Loops

The one-line summary: export 1080×1920, keep Shorts under 3 minutes (under 60s if you want the loop), and treat captions as burned-in unless you're uploading specifically to YouTube.

The caption gotcha (why one master file isn't enough)

YouTube is the only one of the three that reliably accepts sidecar subtitle files — you can upload an .srt or .vtt alongside the video and viewers can toggle captions on/off. Reels and TikTok effectively want captions in the pixels: their editors have auto-caption features, but those are generated per-upload and often mangle product names, acronyms, and technical terms — exactly the words that matter in a B2B or creator-economy clip.

In practice, that means the same 45-second clip needs two variants for a professional rollout:

Burned-in captions (styled, word-synced) — for Reels, TikTok, and Shorts viewed with sound off, which is most of them.
Clean video + SRT/ASS sidecars — for YouTube uploads where you want toggleable captions and searchable transcript text.

Why caption accuracy and sync matter

Three things separate captions that help retention from captions that hurt it:

Word-level sync. A caption line that appears 300ms after the word is spoken reads as a mistake. Word-timed captions keep the eye and ear aligned.
Line length. 2–3 words per line at 40–60 chars total keeps reading speed comfortable on a phone screen.
Keyword accuracy. Auto-caption engines hear "ClipForge" as "clip forge" or worse. For product names and technical terms, machine transcription needs a correction pass or a vocabulary hint.

Practical export recipe (one pipeline, three platforms)

The workflow we use: cut each clip at 1080×1920 · burn word-synced captions into the Shorts/Reels/TikTok master · export a clean master + SRT + ASS for YouTube · keep every clip under 60 seconds so it loops everywhere. That's one pipeline, and it produces every variant in one pass.

That's exactly what the studio automates: give us a long-form video, and you get back platform-ready clips — captioned MP4s with word-synced burned-in captions, plus clean SRT/ASS sidecar files for YouTube — with zero minutes of your time. A real sample of the output is on the demo page, captions burned in from a 6-minute talk.

Skip the spec sheet — let the studio handle it. Pay with BTC, ETH, or SOL and the deliverables are produced automatically. No account, no subscription.

Order on the storefront → (Studio Pro: 2 clips with burned-in captions + full social pack)

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