How to turn a long video into shorts

Step by step

1. Open the long videoDrop it into the editor. It opens in your browser, with nothing to install and no account needed.
2. Find a moment that stands aloneLook for one complete idea with a strong first sentence: a tip, a story, a surprising answer. Note where it starts and where it ends.
3. Trim to itMove the playhead to the start and press S to split; do the same at the end. Select the parts you don’t need and press Shift+Delete to remove them and close the gap.
4. Switch to 9:16Click an empty part of the timeline and choose 9:16 under Format in the right-hand panel. Select the clip, choose Fill, then drag the video on the preview so the speaker is centred.
5. Add a hook and captionsPut a short headline near the top with the Text tab, then add captions — typed by hand, or with Auto captions on a paid plan.
6. Export, then repeatExport the MP4. For the next clip, undo back to the full video (Ctrl+Z) or start a new project with the same file, and cut the next moment.

What makes a good short

A short isn’t just a piece of a long video; it has to work for someone who has never seen the rest. Before you cut anything, check the moment against these points:

• It opens strong. The first sentence makes a claim, asks a question or starts a story. Cut the “so, um, as I was saying” that comes before it.
• It holds one idea. If you need to explain the context first, it’s probably not the right moment.
• It ends cleanly. Stop on the punchline or the conclusion, not halfway into the next topic.
• It fits the platform. Length limits change, so check each platform’s current limit before you cut.

Reframing a landscape speaker for 9:16

Cropping a 16:9 video to 9:16 keeps only about a third of the width, so framing matters. With one speaker, centre their face and keep a little space above the head. With two people, split the clip where the speaker changes and move the frame for each part, or use keyframes to pan smoothly from one to the other.

If cropping loses too much, choose Fit instead to show the whole picture, then use the space above and below for a headline and captions. That layout works well for podcasts and screen shares. For more on fill versus fit, see how to resize a video.

The AI way: long video to shorts

Finding the best moments in an hour of footage is the slow part. Long video → shorts transcribes the video, then looks for clips with a strong opening line, one complete idea and a clean ending. You choose how many clips you want (3, 5, 8 or 10), a length range (15–35, 30–60 or 55–90 seconds) and the spoken language.

Each suggestion can be previewed, then opened as a new 9:16 project with captions and an optional headline, ready to edit like anything else. It needs an account on a paid plan and uses about one AI minute per minute of speech from your monthly AI time.

Captions are not optional

Short-form feeds autoplay with the sound off, so a clip without captions loses most of its audience in the first second. Use big, high-contrast captions with a few words at a time, and keep them above the bottom ~20% of the frame where the app’s buttons and description sit. How to add subtitles to a video covers both the free and the AI way.

Posting your clips

CutLuma doesn’t post for you: download each MP4 and upload it to YouTube Shorts, TikTok or Instagram Reels yourself. The same 1080×1920 file works on all three. Give every clip its own title and description instead of “part 3”, and spread them out over days rather than posting them all at once. The YouTube Shorts and podcast pages have more ideas.

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