The honest answer to “how long should my video ad be” is: shorter than you think. But it depends on the platform and where the viewer is in your funnel.
The general rule
For cold paid-social traffic, aim for 6–15 seconds. Attention on TikTok, Reels and Shorts is brutal, and a tight ad that lands the hook, product and CTA quickly almost always beats a long one. If you can cut a second, cut it.
By platform
| Platform | Sweet spot |
|---|---|
| TikTok | 9–15s |
| Reels / Stories | 6–15s |
| Facebook / Instagram feed | 10–20s |
| YouTube Shorts | 10–20s |
| YouTube in-stream | 15–30s |
By funnel stage
Cold audiences need short and punchy — you’re buying a first impression. Retargeting audiences already know you, so a slightly longer ad that stacks proof and an offer can work harder.
Front-load everything
Whatever the length, the first second carries the ad. Lead with the hook and show the product early — most viewers who leave do so before the halfway mark.