How to Change Composition Duration in After Effects

Adjusting the duration of an existing composition in Adobe After Effects is a fundamental task that allows you to lengthen or shorten your project's timeline as needed. This guide covers the quickest ways to change composition duration using composition settings, keyboard shortcuts, and work area trimming, as well as how to extend your layers to match the new timeframe.

Method 1: Using Composition Settings (Best for Exact Timecode)

The most direct way to change the duration is through the Composition Settings dialog box.

  1. Open the composition you want to edit by double-clicking it in the Project panel or selecting its tab in the Timeline panel.
  2. Open the Composition Settings window using one of these options:
    • Go to the top menu and select Composition > Composition Settings...
    • Press Ctrl + K (Windows) or Cmd + K (macOS).
  3. In the settings window, locate the Duration field near the bottom.
  4. Enter your desired duration using the timecode format: Hours : Minutes : Seconds : Frames.
    • Tip: You can also type simplified numbers. For example, typing "3000" in a 30 fps project sets the duration to 30 seconds.
  5. Click OK.

Method 2: Trimming Comp to Work Area (Best for Shortening)

If you need to quickly shorten your composition to a specific visual point, use the Work Area bar.

  1. Move the Current Time Indicator (playhead) to where you want the composition to end.
  2. Press N on your keyboard to set the end of the Work Area to the playhead's position (or press B to set the start point).
  3. Right-click the gray Work Area bar directly above the timeline layers.
  4. Select Trim Comp to Work Area.

Adjusting Layers After Extending Duration

When you make a composition longer, existing layers do not automatically stretch to fill the newly added time. To prevent the screen from going black:

  1. Select the layers you want to extend in your timeline.
  2. Move the playhead to the very end of the newly extended composition.
  3. Press Alt + ] (Windows) or Option + ] (macOS) to snap the out-point of the selected layers to the playhead, or simply click and drag the right edge of each layer bar to the end of the timeline.