How to Change Composition Resolution in After Effects

Changing the resolution of a composition in Adobe After Effects is a straightforward process whether you need to alter the final output dimensions of your video or temporarily reduce playback resolution to improve system performance. This guide covers the exact steps to modify your composition dimensions via the Composition Settings panel and how to adjust the preview resolution in the viewer for smoother editing.

Method 1: Change Output Resolution (Canvas Dimensions)

To permanently change the width, height, or pixel aspect ratio of your project:

  1. Select the composition you want to edit in the Project panel or open it in the Timeline.
  2. Go to the top menu and select Composition > Composition Settings, or press the keyboard shortcut Ctrl + K (Windows) or Cmd + K (Mac).
  3. In the Basic tab, locate the Width and Height fields under the Video section.
  4. Enter your new pixel values. If you want to change dimensions independently, uncheck the Lock Aspect Ratio checkbox.
  5. Alternatively, select a standard resolution from the Preset dropdown menu (such as 1080p, 4K, or social media formats).
  6. Click OK to apply the changes.

Note: Changing the composition dimensions will not automatically scale your existing layers. To scale an existing layer to fit the new resolution, select the layer and press Ctrl + Alt + F (Windows) or Cmd + Option + F (Mac).

Method 2: Change Preview Resolution (Playback Performance)

If you only want to change the rendering resolution to speed up playback and RAM previews without altering the final export quality:

  1. Look at the bottom of the Composition panel.
  2. Locate the Resolution/Down Sample Factor dropdown menu (it typically displays Full, Half, Third, or Quarter).
  3. Select a lower resolution:
    • Full: Renders every pixel (best quality, slowest performance).
    • Half: Renders one-quarter of the pixels (faster preview).
    • Third: Renders one-ninth of the pixels.
    • Quarter: Renders one-sixteenth of the pixels (fastest preview).
    • Auto: Automatically drops resolution when scrubbing or playing back based on your zoom level.

This setting only affects real-time viewport playback inside After Effects and does not affect your final export settings in the Render Queue.