How to Change Composition Size in After Effects

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This tutorial teaches you how to change the size of a composition in After Effects. Compositions, also known as “comps”, in After Effects have a set size when they’re created and here’s how to change it.

Composition Settings Window to Change Comp Size in After Effects

To change the size of a composition in After Effects, first make sure that comp is open. Now use the keyboard shortcut Command+K (Mac) or Control+K (Windows) to open the Composition Settings window. Instead of the keyboard shortcut, you can go to the Composition menu and choose Composition Settings. However Cmd/Ctrl+K is one of those shortcuts you should commit to memory if you plan on using AE often.

Composition menu in After Effects with Composition Settings selected
Learn Cmd/Ctrl+K instead but you can find the Composition Settings under the Composition menu

In the Composition Settings box you can choose a preset size and frame rate setting by choosing one of the options from the Preset: dropdown.

Preset Composition Sizes in After Effects

If you’re brand new to video I know this can be overwhelming. It can vary greatly as to what size video you should choose. However if you literally have no idea, HDTV 1080 29.97 is a pretty solid choice IMO as a standard composition size in After Effects. If that’s too big then I’d recommend HDV/HDTV 720 29.97. The difference between these two is that the “1080” one will be at 1080 resolution — 1920 pixels wide by 1080 pixels tall. “720” will be 1280 pixels wide and 720 pixels tall.

Composition size presets in After Effects’ Composition Settings
You can use a preset size if you’d like

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Custom Composition Sizes in After Effects

Instead of one of the presets you can choose a custom height and width for your composition size in After Effects. Find the Width: and Height: properties and change them as needed. You can click and drag the number value, however this is not very precise. Or you can manually click into one of the numbers and type in a new value. If you want to change the aspect ratio (for example: if you want to do a vertical video instead of horizontal), uncheck the Lock Aspect Ratio box.

If you want to do 9:16 instead of 16:9 for vertical video, uncheck that box then just type in the values into the other box. So Width would be 1080 and Height would be 1920.

Composition Settings to change comp size in After Effects
Or you can choose a custom size for your Composition

Once you’ve changed the size of the composition click the OK button.

After You’ve Changed the Composition Size in After Effects

One warning… If you already have elements in your comp, you’re probably going to have to adjust them. Nothing will happen to them when you click OK but the composition will have a new size. So if your comp was 1920×1080 before and now it is 1280×720, all your layers are going to be too large. You’ll need to scale them down or vice versa if the situation is reversed.

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If you’ve read this tutorial and you still can’t figure it out, please leave a comment and I’ll do what I can to help troubleshoot it. But if you can now change the size of a composition in After Effects, I hope you stick around and check out some of the other After Effects tutorials on my website or consider signing up to get notified about new blog posts and happenings around EVF.

– Josh

2 thoughts on “How to Change Composition Size in After Effects”

  1. If you’re scaling a composition with existing elements and don’t want to resize the elements individually, Go to File>Scripts>Scale Composition.jsx and select the new width, height scale of change you want. No need to manually adjust content, all elements and key frames will scale automatically.


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