Short-Form Video Specs Cheat Sheet: Length, Size, Safe Zones and File Types

One file works on all three short-form apps: a vertical MP4, 1080 × 1920 pixels (9:16), H.264 video with AAC audio, 3 minutes or less. Keep captions and faces in the middle of the frame, away from the bottom and the right edge, where each app puts its buttons and text. If the clip has music and you want it on YouTube, keep it under 60 seconds.

The rest of this page is the reference version, with the reasons behind each rule. When you need every detail for one platform, follow the links to the full size guides.

The one-file spec

If you only remember one table, make it this one.

This matches YouTube’s recommended upload settings (MP4, H.264, AAC, upload at the frame rate you recorded) and TikTok’s developer guidelines, which recommend MP4 and H.264. Filming in 4K is fine, but exporting 1080 × 1920 keeps files small and uploads fast. The apps compress everything for phone screens anyway.

Length limits

Length rules are the ones that change most often, so check your own upload screen if something looks different.

A few details behind those numbers:

• YouTube decides what is a Short from shape and length alone. A square or vertical video of 3 minutes or less is a Short. A horizontal 16:9 video is always long-form. Most songs in the Shorts audio library can be used for up to 90 seconds, some only 60 or 30. How long YouTube Shorts can be covers every rule past the one-minute mark.
• TikTok has raised its limits several times and rolled them out unevenly. For most short-form clips the limit doesn’t matter. What matters is whether people watch to the end, as covered in how the TikTok algorithm works.
• Instagram lets you post long Reels, but if the goal is reaching new people, 3 minutes is the real ceiling. Details are in the Instagram Reels size guide.

The maximum is not a target. A clip should last as long as one complete idea takes. For most beginners that’s 20 to 60 seconds.

Aspect ratios compared

All three apps accept other shapes, but only 9:16 fills the screen.

If your footage is horizontal, crop or reframe it to 9:16 instead of placing it on a background. The horizontal to vertical lesson shows the three ways to do it and when each works.

Safe zones for captions and faces

Every app draws its interface over your video: titles, usernames, captions, sound names, and a column of buttons on the right. None of the three publishes exact pixel values for regular posts, and the overlay shifts with device and caption length. These margins on a 1080 × 1920 frame keep text clear on all three:

That leaves a safe area of about 830 × 1150 px, a little left of center and a little above the middle. Put captions, on-screen text and the speaker’s face there. These are the strictest margins across the three apps, so a clip that fits them is clear everywhere. Per-platform margins are in the size guides for YouTube Shorts, TikTok and Instagram Reels.

Captions and on-screen text

Captions aren’t a platform rule, but they are close to one in practice. Many people start watching with the sound off, and words on screen help them decide in the first second whether to stay.

• Use 1 to 2 lines at a time, 3 to 6 words per line.
• Make the text large enough to read at arm’s length: on a 1080-wide frame, around 60 to 80 px tall is a good starting point.
• Use high contrast: white text with a dark outline or shadow, or a solid box behind it.
• Keep captions in the same spot for the whole clip, inside the safe area.

The captions guide covers tools that do this automatically. If you’re cutting clips from a long video, Short.now reframes them to 9:16 and places captions inside the safe zone for you.

Covers and thumbnails

The cover is the still image people see before they tap, on your profile and in search.

• YouTube Shorts: In the feed nobody sees a thumbnail. It shows on your channel page, in search and on shelves. Pick a clear frame, or add a custom one in the same 9:16 shape. See how to add a thumbnail to YouTube Shorts.
• TikTok: Pick a cover frame when you post and add a short text label so your profile grid tells people what each video is.
• Instagram Reels: Make the cover 1080 × 1920, but keep the title and face in the middle, because the profile grid shows a crop from the center.

Don’t break these rules

Some mistakes don’t just look bad, they cut reach.

• Re-uploading a watermarked file. Instagram makes watermarked and low-resolution Reels less visible. TikTok’s guidelines say reused material with nothing new added isn’t eligible for the For You feed. Always export a clean file from your editor.
• Long clips with claimed music on YouTube. Over 1 minute, a Content ID claim blocks the Short. Use the Shorts audio library, royalty-free music, or keep it under 60 seconds.
• Upscaling a tiny crop. A 608 × 1080 crop from a 1080p horizontal video looks soft when stretched to 1080 × 1920. Film in 4K if you plan to crop to vertical.
• Adding borders or a blurred frame around small video. Instagram lists Reels with borders among those it shows less.

Pre-upload checklist

• 1080 × 1920, 9:16, MP4 with H.264 and AAC
• 3 minutes or less; under 60 seconds if it uses music on YouTube
• Captions and face inside the safe area
• No watermark from another app
• Exported from the original footage, not a downloaded copy
• Checked once on a real phone

What’s next

That’s the end of the platforms module: you know how each feed decides what to show and what format to give it. Module 3 is about what to actually make. Start with 75 short-form video ideas and how to find your own.