How to make YouTube Shorts from your long videos
To turn a long video into a YouTube Short, pick one self-contained moment of 15–60 seconds, reframe every shot from 16:9 to 9:16 so it fills the frame (about a 3.16× zoom, centered on the speaker), add big captions in the middle of the frame, and start on the strongest line. Here's each step, the numbers behind it, and a real Short cut from a 19-minute recording.
1. Pick a moment that stands alone
A good Short makes sense without the rest of the video (finding it with AI): one answer, one tip, one surprising fact, one funny exchange. Good candidates:
- The line you'd quote if someone asked "what was it about?"
- A clear before/after or a reveal.
- A strong opinion, stated in one breath.
If it needs the previous minute to make sense, it isn't a Short.
2. Keep it short
Square or vertical videos up to 3 minutes count as Shorts (for uploads since October 15, 2024), but 15–45 seconds is the sweet spot for most long-video cutdowns: long enough for one complete idea, short enough that people watch to the end. Cut the setup and start on the point.
3. Reframe for 9:16 without black bars
A 16:9 frame in a 9:16 Short has to be enlarged about 3.16× (16/9 ÷ 9/16) to fill the frame. Less than that leaves black bars above and below. At that zoom only the middle third of the original width survives, so:
- Center each shot on the subject, not the middle of the frame.
- For two people, alternate framing on whoever is speaking.
- Check every shot. One shot with an empty frame ruins the Short.
- Watch for letterboxing in the source. Our source video had a thin black band at its top edge, so we zoomed to 3.3× to crop it off.
4. Captions in the middle third
YouTube puts the title, channel name and buttons over the bottom and right side. Put captions in the middle third, 2–4 words at a time, in a bold high-contrast style. Caption styling →
5. A hook in the first second
Open mid-sentence on the strongest line, or with a 1-second text hook ("Astronauts train in caves?"). No logo animations.
How we made ours
From an 87-second YouTube video built from 19 minutes of interviews, we asked:
Make a 45-second vertical YouTube Short from the same edit. Every shot must fill the 9:16 frame with no black bars: zoom about 3.16x and keep her face centered. Keep the captions in the middle third, clear of the YouTube buttons.
Novacut kept nine answers (41.8 seconds), dropped a line that repeated an earlier point, and reframed every shot on her face. One follow-up pushed the zoom to 3.3× to hide the thin black band in the source.
FAQ
How long can a YouTube Short be?
Up to 3 minutes, if the video is square or vertical. One catch: a Short over one minute with an active Content ID claim (for example, popular music) is blocked until the claim is resolved. For cutdowns from long videos, 15–45 seconds usually performs best because viewers finish and rewatch.
What resolution should a Short be?
Vertical 9:16, ideally 1080×1920. Square videos also count as Shorts but leave empty space above and below in the player; horizontal videos aren't Shorts at all.
Can I post the same clip to TikTok and Instagram Reels?
Yes. The same 9:16 file works, but check that captions and text sit clear of each platform's buttons. TikTok tips →
Why does my Short have black bars?
The picture is fit inside the frame instead of filling it. Zoom about 3.16× from 16:9 (or crop each shot) so the picture covers the whole 9:16 frame.
Sources: YouTube Help, Understand three-minute YouTube Shorts. Checked October 2026.
Demo footage: NASA interviews with astronaut Jeanette Epps (public domain). NASA does not endorse Novacut.