Reel speed 0.5x to 3x: burn captions after the final speed change

Burn captions after the last speed change, never before it. Instagram's Reels guide (read 2026-10-05) lists speed adjustment from 0.5x to 3x among the built-in editing tools, and burned-in captions are part of the picture, so a speed change in the app speeds up the text with the video. A line that stays on screen for 1.5 seconds is on screen for 0.5 seconds at 3x, which is too short to read.

The fix is an order of operations. Finish the edit, including every speed change, then run one caption job on the finished clip.

The arithmetic of speed and reading time

Playback speed divides time on screen. A caption phrase shown for T seconds in the source is shown for T divided by the speed factor in the result. At 0.5x the same phrase stays for twice as long, which feels slow but is readable. At 3x it shows for a third as long.

A reader needs a minimum time for a short phrase, and that minimum does not shrink because your clip is fast. So a phrase that was comfortable at normal speed can become unreadable at 2x or 3x. The table shows how long a 1.5 second phrase stays on screen at each end of Instagram's range.

What Sume does for captions

Sume's standalone video captions job takes a public HTTPS video_url and burns captions into the picture. It costs $0.20 for a clip of up to 60 seconds under the current fixed estimate, and the price is the same whichever style you choose. Because the text is part of the output file, there is no separate caption track that a later edit could re-time. That is the reason to run the job last.

You can control how fast the text moves with the design.phrasing fields, max_words, max_chars and pause_seconds. Fewer words per phrase give a faster flow of short lines, which holds up better when a clip is going to play at a high speed. If you already ran a caption job and only want another look, send source_caption_id with a new style. Sume reuses the word timings it already has, so it does not transcribe twice. The price is the same, because a restyle is still a render.

• Edit first. Trim, reorder and set every speed change.
• Export the clean cut and host it at a public HTTPS URL.
• Run one caption job on that file, and keep the clean file for a restyle.
• Check the result at the speed the viewer will see it.

If the speed change happens inside Instagram

Some creators change the speed after upload, inside the app, after the file has left your pipeline. In that case your captions will speed up with the clip, and you cannot re-time them from outside. Two choices work. Apply the speed change before you export, so the file you caption already has its final timing, or burn captions with a generous minimum time per phrase and accept that the 0.5x end will feel slow.

A third choice is to skip burned-in captions for that Reel and use Instagram's own subtitle generation, which the guide says creates subtitles from the audio and lets you edit them before you customize the style. That keeps timing inside the app, but you lose control of the look and of the words, such as brand names.