Insider Tips: Calculate the Perfect Composition Length in After Effects

Every week, Frame.io Insider asks one of our expert contributors to share a tip, tool, or technique that they use all the time and couldn’t live without. This week, Laurence Grayson shows you how to calculate exactly how long a precomp needs to be with After Effects layer markers.

---

How to find the perfect composition length in After Effects

Precomping is among After Effects’ most useful tools, allowing you to group a bunch of layered elements into a unique composition, which can then be treated as a single layer in another comp.

The most common way to create an After Effects precomp is to select some layers in your current composition and select Pre-compose (Shift+Option+C / Cmd+Shift+C) to move them into their own composition. But if you have a time-specific gap that needs to be filled, you’re more likely to start from scratch with a new composition, instead.

In which case, you’ll need to use a little-known function in After Effects’ UI that lets you easily calculate the exact time your composition needs to be. No calculations needed.

Calculating duration between markers in After Effects

1. In the main composition, select a layer and hit Ctrl/Alt+8 to create layer markers at the In and Out points for the area you need to fill. (Note that composition markers don’t work.)
2. Make sure your workspace has the Info panel visible.
3. Hold down Opt/Alt while clicking on the first marker, then the second marker.
4. The Info panel will then display the exact duration between these two markers in timecode or frames depending on the project settings.

You can now enter this value in the New Composition panel to create a new comp that exactly matches this duration.

Bonus point

But wait. There’s more. Leaving these markers in place makes it easier to drop your new comp into place because it’ll snap to them.