Ideal Video Length by Platform: What the Retention Data Actually Says

"How long should my video be?" gets asked constantly, and it almost always gets answered with a specific number — 8 minutes for YouTube, 15 seconds for TikTok, and so on. Those numbers aren't wrong exactly, but treating them as a target misses the actual mechanic underneath them: length isn't good or bad on its own, it's good or bad relative to whether the content earns every second of it.

Length interacts with retention rate, it doesn't replace it

A shorter video with the same amount of dead air will still lose viewers at the same rate a longer version would — it just runs out of runtime before the retention curve fully bottoms out, which can make a padded video look healthier than it actually is. This is the trap in chasing a length target directly: you can hit the "ideal" number and still be publishing a video with the same structural problems, just compressed into a shorter window.

The more useful framing is that length should be a downstream decision, set by how much material actually earns continued attention, not an upstream target you write and edit toward.

Short-form: TikTok, Reels, Shorts

On feeds where the next video is a flick away, the practical ceiling on length is set by how much genuinely new information or visual change you can deliver per second, not by a platform rule. Most short-form that underperforms isn't too long in an absolute sense — it's padded relative to its length, with a hook that's earned attention the middle doesn't spend efficiently. A tight 12-second video will usually outperform a padded 30-second one covering the same idea, even though the shorter run time looks like less content.

Mid-form: standard YouTube videos

This is where "ideal length" advice gets the most inconsistent, because the honest answer is that a well-earned 20-minute video will retain better than a padded 6-minute one. The reason 8–12 minutes gets cited so often isn't that it's magically optimal — it's that it's a length a lot of topics can fill with genuinely earned content without needing filler, and a length viewers are willing to commit to before they've decided whether they trust the video. Topics that warrant more depth can earn a longer runtime; topics that don't shouldn't be stretched to hit a number.

Long-form: podcasts, tutorials, deep dives

Long-form retention curves are naturally more forgiving because viewers who click into a 45-minute video have already filtered themselves for genuine interest — the audience arriving is different from the audience arriving for a 90-second clip. This doesn't mean length stops mattering; it means the bar for "earning" each stretch shifts from second-by-second novelty to sustained, real depth. A long-form audience will tolerate a slower pace than a short-form one, but they won't tolerate padding any better — they'll just take longer to notice it.

The real question: has this cut earned its length?

Instead of asking "how long should this be," a more useful question while editing is "is there a point earlier than my current ending where this could reasonably stop?" If the answer is yes, that's usually a sign the video is running past what its content actually earns, regardless of whether the total runtime looks "ideal" on paper. Cutting to that earlier point — rather than trimming evenly across the whole edit — tends to fix a length problem without gutting the material that's actually working.

The hard part is that it's genuinely difficult to feel this out on your own footage, because you already know what's coming in every section, which makes padded stretches feel shorter to you than they'll feel to a first-time viewer. Axony analyzes the finished edit and produces a predicted, second-by-second attention and retention curve, so a stretch that's running past what it's earned shows up as a specific dip — giving you a concrete, evidence-based answer to "should this be shorter" instead of a guess based on a generic length rule.