What this guide does: Explains why a vertical video is watched or skipped in its opening seconds, and gives the timing arithmetic to build one that gets past it. Read it before writing a hook, choosing a length, or diagnosing a reel that got no views.
Both platforms decide a video’s reach from a small first batch of viewers and from what each of them does in the first seconds. Nothing after second three matters to someone who left at second two. Everything below follows from that.
Each claim carries how we know it: measured (we ran it and wrote the number down), reproduced (we made the mistake and watched it happen), published (the platform or a cited source says so, we have not tested it).
Frame 0 is the cover, so it must already be readable
Reproduced, twice, on two different accounts. The feed shows the video’s first frame as its poster image. A hook that fades in from black has a black cover. A hook that animates up from 0.42 opacity reads as washed-out grey for the first half second - which is inside the window that decides whether anyone stays.
Place the first card. Do not animate it in. Light it at 0.7 opacity or more, and make it true at t=0.
The opener has to end before second three
Reproduced. A hook card held for 3.3 seconds puts the first cut at 3.1 seconds, so the entire skip window contains one motionless card. Nothing has happened yet when the viewer decides.
Size the opener to its own reading load with a floor of 1.6 seconds, and check that the first cut lands under three. A cut inside the window is the cheapest signal you have that this video is going somewhere.
Length: one measured result, and its confound
Measured, on one of our own accounts, 2026-08-29. A batch cut to 15.5 seconds drew 113-162 views on an account with a single follower. The 29-32 second cuts that followed on the same account drew 6-22, and one sat at 6 views after 29 hours - a distribution collapse rather than a slow start.
State the confound honestly: three things changed in that batch at once (background, word density, length). Length is the reversible one, not the proven one. That account now runs a 10-13 second test. Neither band is a benchmark, and anyone quoting 15.5 seconds as an optimum - including us - is over-reading a single comparison.
The timing arithmetic
Reading load, not taste. These are the holds that stop a card from reading faster than it is shown.
| hold | why | |
|---|---|---|
| any word | 300 ms | silent reading speed on a phone |
| any character | 52 ms | a compound noun is one word and twenty letters, so take max(words, chars) |
| opener | 1.6-2.8 s | reading load + 0.5 s, and the first cut must land under 3 s |
| body or turn | 2.4-4.2 s | reading load + 0.7 s |
| a big number | 2.6-3.8 s | the number reads at a glance, its label does not |
| closer | 3.6-5.0 s | reading load + 1.3 s; this is the card people screenshot |
| overlap | 200 ms | each card starts before the previous one leaves |
Word budgets per card, never totalled: hook 3-11, body 3-14, closer 4-16. A 3.5-second card holds roughly 10 words or 55 characters at a comfortable size. Past that the card reads faster than it holds, and the viewer waits - which is the same experience as being bored.
What a hook is, and is not
- A sentence your buyer has actually thought, or the sharpest fact stated flat. A scene or a number. It opens a loop the closer shuts.
- Not a “how to”. That creates an expectation of information, and information can be postponed. Not a question. Not “did you know”.
- Recognition stops a scroll; tempo does not. A harvested ten-word hook beat an invented four-word one on our own account (reproduced). Hooks come from what people actually said - forum threads, reviews, support mail - not from the bank of phrases that sound like hooks.
- The second card is a second hook. It has to work cold, with the first card gone. On carousels the platform literally re-serves from the second slide; on video, the first cut is the same second chance.
- The closer is flat and screenshottable, and it lets the product do the work rather than issuing an install instruction.
The kill rule
Published, from platform averages rather than our own numbers: under 25% of viewers still watching past three seconds, keep the body and replace the hook. Around 30% is healthy and 40% is exceptional on TikTok.
Two guards on that rule. Never judge a format before ten posts, and never judge a new account before 90 days - distribution is a power law, and a handful of posts carry most of the reach. Reading the first three posts of a new account is reading noise.
Where that number actually lives
This matters more than it sounds, because the metric the kill rule needs is the one hardest to get:
- Views, likes, comments, shares, saves and reach come back through the platforms’ public APIs, and Sprid stores them per post.
- Three-second hook rate and the retention curve exist only inside the native Instagram and TikTok insights screens. There is no API field for them as an organic number. If you need them, you open the app.
- Average watch time is available through both business APIs, which makes
average watch ÷ durationthe honest proxy you can automate. - Taps through to your site or store are the number that pays. The rest are directional.
One picture, many languages
The reason a demo video is usually made once is that the work is a person holding a phone. Split it instead: the wordless part (the footage, the gesture script, the photographs) and the worded part (the captions and cards, bound to marks in the footage rather than to timestamps).
The rule that makes it hold: no word is ever inside a picture. A wordless cutaway serves every language you have a string table for, so a seventh language costs its translation and one render rather than a second shoot.