This tutorial is on how to change the duration or length of a Composition in After Effects.

Set Duration for a New Composition

First, create a new Composition. You can do this by hitting Command+N if you’re on a Mac or Control+N if you’re on a Windows computer. That will bring up the Composition Settings for the new Composition we’re creating.

Give your Composition a name, set the size, frame rate, and duration. The “duration” is how long the Composition will be. Unlike programs like Premiere or Media Composer, the timeline in After Effects will not automatically expand when there are clips longer than the Composition’s duration in the timeline. IMO this is neither good nor bad, just a difference we have to remember and combat with the next section of this article.

Composition Settings in After Effects to change Duration of Comp
Set the duration of your Composition in the Composition Settings

The “duration” will probably default to say something like “00:00:30:00”. This means it’s 30 seconds long. These numbers translate to “hours:minutes:seconds:frames”. So “01:05:25:06” means the Composition is one hour, five minutes, 25 seconds, and six frames long. When done click OK. You’ve now set the duration for a new Composition in After Effects. Now let’s change the duration of the Composition.

Additional Suggested Viewing: The Replace Layer Shortcut in After Effects Tutorial

Change the Duration or Length of an Existing Composition in After Effects

With the Composition open, use the keyboard shortcut Command+K if you’re on a Mac or Control+K if you’re on a Windows computer to open the current Composition’s Settings. You are taken right back to where we were a moment ago, in the Composition Settings.

From here change the duration to whatever you need it do change to.

And now you’ve learned how to change the duration of a Composition in After Effects. Give me a shout in the comments if you have any questions!

Did you enjoy this tutorial? If so, I’d love to keep in touch. All you have to do is go here to stay in the loop on new blog posts, tutorials, and announcements.


– Josh