Length matters more than people think — for both reach and pay. Two rules:
- Facebook reels: 11–14 seconds tends to be the sweet spot — long enough to qualify for monetization (Facebook needs 10s+) and to bank watch time, short enough to hold people to the end.
- Instagram reels: 9–12 seconds tends to peak for reach.
- Almost never go over ~14 seconds unless the payoff truly needs it — completion rate falls off, and completion is what the algorithm rewards.
Heads up · On Facebook, under 10 seconds can't earn at all — it fails the monetization length rule no matter how good it is. If you're posting 7-second clips to Facebook, they're reach-only.
Note · These are strong starting points, but your own account has the final say — Merge learns your real length-vs-performance curve and adjusts the guidance to you.