X video ads loop under 60 seconds: design the last frame of a 45 s ad

X loops video ads shorter than 60 seconds and plays longer ones once. So a 45-second ad should end on a frame that flows into its opening, and a 90-second ad should end on a closing card with the call to action. X also recommends 15 seconds or less, so most ads will loop.

The rule in X's words

The X creative specs page states: videos will loop if the video length is under 60 seconds. It supports lengths up to 2:20 and recommends 15 seconds or less. It does not say how many times a loop repeats, so do not plan around a count.

Make the loop seamless

There are two practical edits. First, make the last second visually similar to the first second: same background, same framing, or a cut on motion. Second, if the video has voiceover, end the audio on a pause rather than mid-word, because the audio restarts with the video.

On Sume, trim a candidate ending with video trim: send start and duration and get a new MP4. The default exact precision is frame-accurate. To compare the end of the clip with its start, extract two stills with video frames at times [0, last second] and look at them side by side. Video frames returns images at source size, so you see what the viewer sees.

Cost of testing endings

If you want to try three alternative endings, you cut three trims. Each trim is $0.02 per job, so three variants cost $0.06. Joining a different last slot with the body through a timeline render is $0.10 per output minute rounded up, with a one-minute minimum, so a 45-second ad is $0.10 per variant. Three timeline variants are $0.30 (Sume catalog, read 2026-10-08).

Transitions help hide the seam. Timeline slots after the first accept fade, wipeleft, wiperight, slideup, slidedown and dissolve, up to 1 second long. A dissolve is a poor loop device because the first frame of the next play is not part of the same render, so prefer a hard match cut.

When not to loop

A tutorial or a sequence that only makes sense in order should be 60 seconds or longer, or you should end on a still card that works as a freeze. Looping a step-by-step video confuses viewers about where it starts.

A quick check before you upload: read the duration from the probe in Sume video inspect (duration_seconds) and confirm it is under 60 if you want the loop. A render that comes back at 60.02 seconds because of audio padding would sit on the wrong side of X's line, so trim it to 59 seconds with a duration of 59 and probe again. The check costs a few cents of compute and saves a resubmission.