Masks are the most underused tool in CapCut. Most people never open the menu because the name sounds technical, but the idea is simple: a mask hides part of a clip without cutting the clip itself. You’re laying one video on top of another and deciding which window of it shows through. Every “how did they do that” effect in short-form video — split screens, circle reveals, text-behind-person — is a mask plus maybe a keyframe.

Where Masks Live

Masks apply to a clip, and for anything interesting, that clip needs to be an overlay — the layer above your main track. Tap the overlay clip and look for Mask in the toolbar. You’ll get a grid of shapes: linear, circle, heart, star, and so on. The shape is your window; everything outside it becomes transparent, letting the layer below show through.

Two controls matter more than the shape itself:

  • Position and size. Drag the mask around the frame and pinch to resize it — same gestures as normal clips.
  • Feather. Softens the mask’s edge. This single slider is the difference between an effect that looks crafted and one that looks stamped on. More on it below.

There’s also an Invert toggle — it flips the mask so the shape hides the clip instead of showing it. Half the effects I make start by inverting first.

Split Screen in Two Minutes

The classic: two videos playing side by side.

  • Put your first clip on the main track.
  • Add the second clip as an overlay, covering the whole frame.
  • Tap the overlay, choose Mask, pick Linear, and rotate the divider so it sits vertically down the middle.
  • Set feather to a small value — just enough to avoid a razor edge.

Rotate the linear mask to any angle for diagonal splits, or use two overlays with two linear masks for three- and four-way screens. The honest warning: split screens hold attention for about three seconds. Use them as a moment — “both options,” “before and after” — not as a layout for the whole video.

The Circle Spotlight

A circle mask over a darkened background is a cheap way to add drama:

  • Duplicate your clip: one copy on the main track, one as an overlay.
  • Darken the main-track copy with the Adjust menu (drop brightness and exposure).
  • On the overlay copy, apply a Circle mask, position it over your subject, and feather generously — 15–25% reads as a spotlight, 0% reads as a sticker.

Now the upgrade: add keyframes to the mask’s size and position so the spotlight grows or drifts to follow your subject. If you haven’t used keyframes yet, my beginner keyframe guide covers the mechanics — masks animate with exactly the same keyframe system as position and scale.

Build Your Own Reveal Transition

This is my favorite masks trick, because it replaces the preset transitions everyone overuses:

  • Clip B sits as an overlay above clip A, masked down to a sliver at the edge of the frame (linear mask).
  • Keyframe the mask’s position at the start, then move it across the frame and keyframe again.
  • On playback, clip B wipes across to reveal itself — at exactly the speed and direction you chose.

Because you control the motion, you can match the direction of movement in the footage — a wipe that follows a camera pan feels intentional in a way no preset transition can. For a deeper look at choosing between custom reveals and presets, see the transitions guide.

Feather: The Amateur-to-Clean Dial

Hard mask edges are the tell of a beginner effect. A little feather blends the masked clip into the layer below, the way real light behaves. For spotlights and dissolves, feather 15–25%. For crisp geometric splits, keep it near zero but not exactly zero — a 1–2% feather avoids the aliased, staircase-looking edge you get on diagonal lines. And when an effect still feels pasted on, the problem is usually light, not the mask: match brightness and white balance between the layers and most seams disappear.

What Masks Can’t Do

A mask is a static window — it doesn’t know what’s inside it. If you want “text behind a person,” that’s the Cutout tool on the person, not a mask. If you want the mask to follow a moving subject automatically, that’s keyframes by hand. Masks are dumb shapes; the craft is in what you do with them. Open the menu, invert a circle, feather it, and you’ve already made something most people scrolling past haven’t seen.