How to Scale a Mask in After Effects

Introduction

Masks in After Effects allow you to control visibility, create reveals, and isolate parts of a layer, but sometimes you need to resize a mask without affecting the layer itself. Scaling a mask works differently from scaling a layer because masks are vector paths attached to a layer. In this tutorial, you’ll learn the correct ways to scale a mask cleanly and precisely.

Method 1: Scale a Mask Using Free Transform

Step 1: Select the Layer

Click the layer that contains the mask in the Timeline panel so that its properties become active and editable.

Step 2: Reveal the Mask Path

Press M to reveal the Mask properties, then click on Mask Path to make sure the mask outline becomes visible in the Composition panel.

 

Step 3: Activate the Mask Selection

Use the Selection Tool (V) and click directly on the mask path in the Composition panel so that all mask vertices are selected.

Step 4: Use Free Transform

Press Ctrl + T (Windows) or Cmd + T (Mac) to activate Free Transform for the mask, then drag the corner handles to scale the mask proportionally.

Step 5: Constrain Proportions (Optional)

Hold Shift while dragging a corner handle if you want to maintain the mask’s original proportions during scaling.

Method 2: Scale a Mask Precisely via Mask Path

Step 1: Select the Mask Path

Press M, click on Mask Path, and ensure all mask points are selected in the Composition panel.

 

Step 2: Adjust Vertices Manually

Drag the selected mask points outward or inward to resize the mask manually if you need non-uniform or custom scaling.

Step 3: Animate the Mask Scale (Optional)

If you want to animate the mask resizing, click the stopwatch next to Mask Path and adjust the mask size at different points in the timeline to create keyframes.

Important Notes

Mask scaling does not affect the layer’s Scale property, and transformations applied to the layer will affect the mask along with it because the mask is attached to the layer.

Conclusion

To scale a mask in After Effects, select the Mask Path, use Free Transform for proportional resizing, or manually adjust the vertices for custom control. Understanding the difference between scaling a mask and scaling a layer ensures precise edits and cleaner motion design workflows.