How long should a TikTok, Reel or Short be?

“How long should my video be?” is really two questions: what does the algorithm reward, and what does your idea need? The honest answer, the shortest cut that completes the idea, sounds like a dodge, so let’s make it concrete.

What the platforms actually reward

Short-form ranking runs on watch time and completion together: how long people stay, whether they finish, whether they replay. Mosseri, February 2025: “we look at not only the percentage of a video that was watched, but also the number of seconds”. TikTok counts replay time inside play time.

Length only wins when the extra seconds hold. A 9-second clip replayed once carries about 13 seconds of watch time; a 45-second clip abandoned at the 60% mark carries 27. The short one wins on completion, the long one on watch time. That is exactly why one number can’t decide your edit.

Padding is still the expensive mistake. But short is not automatically the safe bet. On Buffer’s 2025 sample of 1.1 million TikToks, videos over a minute correlated with 43% more reach and 64% more watch time than 30–60s clips, and Buffer’s own read is that length “is just one factor in a complex algorithm, and it’s unlikely to be the make-or-break element”.

• Under 15s: the loop zone: single joke, single reveal, single before/after. Highest rewatch potential, weakest for trust-building.
• 15–35s: the sweet spot for tutorials, product demos and storytimes with one twist. Long enough for proof, short enough to complete.
• 35–90s: earns its length only with strong narrative pull; expect a steeper drop-off, and the payoff is total watch time, not completion rate.
• 90s–3min: allowed on all three now: Reels and Shorts both cap at three minutes, and TikTok goes far past that. You are competing with long-form pacing on a short-form feed.

Choose by goal, not by habit

• Reach: cut to the loop zone; trim until removing one more second breaks the idea.
• Conversion: 15–35s: hook, problem, one proof moment, soft CTA (see our UGC ads guide).
• Audience-building: longer is fine if every 5-second block earns the next; structure it with the 3-beat script.

The right length is the shortest version that completes the idea, then one second shorter than feels comfortable.

Length norms also drift with trends. Formats themselves carry an expected duration. Admetra’s trend breakdowns show the typical cut length for each rising format, so you can start from what the format expects instead of guessing.