How to loop animation in After Effects with loopOut

What does the loopOut expression do in After Effects?

loopOut is an After Effects expression that repeats a property's keyframes. A short animation keeps repeating, and you never copy keyframes by hand. The line mouzeclick's mouzerun Loop starter writes is loopOut('cycle').

The loop type is the word inside the brackets. mouzeexpr's Loop expression lists four: cycle, ping-pong, offset and continue. Each one changes how the repeat behaves. The fastest way to learn the difference is to apply one, preview, switch and preview again. The steps are further down.

This page quotes only the code our own panels write, plus the steps inside those panels. For the syntax in your version, see Adobe's expression language reference. To type expressions yourself, start with our guide on how to add expressions in After Effects.

A note before the steps: we make mouzeclick. Its After Effects extensions, including the two panels on this page, run on Windows and Mac. The After Effects workspace panel mentioned later is Windows only.

How do I loop an animation with one click in After Effects?

Select the keyframed property and click the Loop starter in mouzerun. It writes loopOut('cycle') on that property, so the keyframes repeat. It is the shortest path from a finished move to a looping one.

1. Animate first. Set the keyframes for one full pass of the move, for example a rotation, a scale pulse or a position drift. The loop repeats what is there, so get one pass right before you loop it.
2. Open mouzerun from Window › Extensions. If it is not listed, install the After Effects bridge first (see the install section below).
3. In the timeline, select the property whose keyframes you want repeated.
4. Click the Loop starter button. The property now carries loopOut('cycle').
5. Preview past your last keyframe to check the repeat.

mouzerun is a panel of your own one-click buttons. A button can hold one of five kinds of action: a script, an expression, an animation preset, a menu command or a keyframe ease. It ships with six starter buttons, and Loop is one of them. You can add your own next to it, then export the set and import it on another computer. The full list of what it holds is on the mouzerun feature page.

If you loop the same few properties on every job, keep Loop near the top of the panel. A one-click button beats retyping the same line in every comp.

How do I make a ping-pong loop in After Effects?

In mouzerun, Alt-click the Loop starter instead of clicking it. That writes loopOut with the ping-pong type on the selected property. In mouzeexpr, apply Loop and set its type to ping-pong.

To compare the two types on the same move:

1. Select the keyframed property and click Loop in mouzerun. Preview the cycle.
2. Undo, then Alt-click Loop on the same property. Preview the ping-pong.
3. Keep whichever reads better for the shot.

Two habits help. First, look at your first and last keyframes before you loop, and preview both types on your own move rather than guessing. Second, if you switch types a lot on one layer, use mouzeexpr instead of undoing and re-clicking. There you change the type in its settings and press Update, as the next section shows.

How do I pick cycle, ping-pong, offset or continue?

Use mouzeexpr's Loop expression. Apply it to the keyframed property, choose cycle, ping-pong, offset or continue in its settings, and press Update to switch. Remove takes it off, and Bake to keyframes turns it into plain keyframes.

1. Open mouzeexpr from Window › Extensions.
2. Select the property whose keyframes you want repeated.
3. Find Loop among the ready expressions.
4. Pick a type: cycle, ping-pong, offset or continue.
5. Press Apply and preview.
6. To try another type, change the setting and press Update. You do not need to remove and re-apply.
7. Press Remove to take the loop off, or Bake to keyframes to swap the expression for keyframes.

mouzeexpr holds 24 ready expressions with settings, in five groups. Loop is the one for repeating keyframes. The mouzeexpr feature page lists every item the panel holds.

Here are the ways to get a loop onto a property, side by side (checked on 3 November 2026):

Pick mouzerun when you nearly always want cycle and sometimes ping-pong. Pick mouzeexpr when you need offset or continue, or want to switch types and bake without retyping. Typing it by hand needs nothing beyond After Effects, so learn the line even if you use a panel.

How do I install the loop panels on Windows and Mac?

Install mouzeclick, press Install After Effects bridge on the app's Tool wheel page, and restart After Effects. mouzerun and mouzeexpr then open from Window › Extensions. The steps are the same on Windows and Mac.

1. Get the key and download links by email. The 3-day trial needs no card.
2. Install the app and paste the key. There is no driver. Apple has not notarized the Mac app yet, so macOS asks you to allow it the first time. The four Mac steps are on installing mouzeclick on a Mac.
3. On the app's Tool wheel page, press Install After Effects bridge. One bridge panel serves Premiere Pro and After Effects at once.
4. Restart After Effects.
5. Open mouzerun or mouzeexpr from Window › Extensions.
6. Keep mouzeclick running while you work. Updates refresh the panels by themselves.

These panels are extensions, not effect plug-ins, so they open under Window › Extensions. If you are unsure what kind of file you are dealing with, our page on plugins, scripts and extensions in After Effects explains where each one lives. The cards for all 22 extensions are on the extensions page.

Why is my After Effects loop not working?

Usually the panel is not loaded, there are no keyframes to repeat, the wrong property is selected, or a type change was not applied. Work down this list.

• The panel is missing from Window › Extensions. Check that you pressed Install After Effects bridge, then restarted After Effects. Make sure mouzeclick is running in the tray (Windows) or the menu bar (Mac).
• Nothing repeats. The loop repeats keyframes, so the property needs a keyed move to work from. Check that the keyframes are on the property you selected, not on a neighbouring one.
• The wrong property moves. The expression goes on the property you selected. Select the keyframed property itself, then apply again.
• You changed the type and nothing happened. In mouzeexpr, a new setting takes effect when you press Update.
• The loop looks wrong at the seam. Try another type and preview each one before you change your keyframes.
• Your After Effects version. mouzeclick publishes no minimum version. Every panel was run tool by tool in After Effects 26.5 on Windows, in both After Effects expression engines. On an older version, check it during the 3-day trial.
• The connection dropped. mouzeclick needs an internet connection while it runs, because the licence lives in your account. If the connection drops, its mouse shortcuts pause until it returns.

If you typed the line yourself and After Effects shows an error, compare it with Adobe's expression language reference for your version. Then try the panel's version on a copy of the layer to see whether the problem is the code or the keyframes.

Should I keep the loop live or bake it to keyframes?

Keep it live while the timing is still changing, and bake it once the move is locked. In mouzeexpr, Bake to keyframes replaces the expression with keyframes you can edit one by one.

A live loop follows your edits. Move the original keyframes and every repeat follows. That is why you loop early and adjust the first pass, not the copies. Baking gives you plain keyframes. Use it when you want to break the pattern in one place, such as an extra-big pulse on the beat, or to nudge a single repeat by hand.

Shape the easing on the first pass, then loop it, so every repeat carries the same curve. Our pages on Easy Ease in After Effects and the 44 ready easing curves cover that step. On Windows, the After Effects workspace's Easing lab can also copy a curve as an expression.

Can I put looping and other expression work on mouse buttons?

Yes, for the keyboard side of the job. The mouzeclick mouse app puts any shortcut, macro or typed text on a mouse button, per app, on Windows and Mac. The Loop button itself lives in the mouzerun panel, so you click it there.

• Per-app buttons. Mouse 4 can do one thing in After Effects and another in every other app. It switches the moment you change windows.
• Eleven slots per button. Tap, hold, hold and move in four directions, a chord with another button, or hold and scroll.
• Shortcut library. 309 built-in shortcuts on Windows, 44 of them for After Effects. A shortcut you record yourself sits next to them in the picker.
• Options wheel. 48 favourites per app on three rings, opened with F8 (Fn + F8 on a MacBook keyboard), Ctrl + right click or a side button.
• Typed text. A macro can type text, so you can put a loopOut line you use often on a button or the wheel. Open the expression field yourself, then press the button.

The After Effects Tool wheel adds 114 tools in 13 groups, opened with F10 or a held right button. See the After Effects radial menu page. For the native keys worth putting on buttons, start with our list of After Effects keyboard shortcuts.

Which other After Effects expressions pair well with a loop?

Wiggle and bounce are the usual partners. A looped pulse with a little wiggle on top looks less mechanical, and a bounce at the end of each pass gives a looped move some weight.

• The wiggle expression, including one-axis use and looping a wiggle.
• The bounce expression for an inertial settle after a move.
• Our expressions library guide covers the workspace Library's 25 recommended expressions (Windows only), Type studio's expressions and mouzeexpr's 24.

Keep one rule: loop the keyed move, and layer the other expressions on separate properties where you can. That way each one can be removed or baked without touching the others. In mouzeexpr, every ready expression has the same Apply, Update, Remove and Bake to keyframes buttons, so the workflow is the same for each.

Where mouzeclick fits (we make it)

You do not need mouzeclick to loop animation. loopOut is part of After Effects, and typing it by hand costs nothing beyond After Effects itself. mouzeclick helps if you loop a lot and want it on a click, or want to switch loop types and bake without editing code.

• What you get for looping: mouzerun's Loop starter (cycle on click, ping-pong on Alt-click) and mouzeexpr's Loop (cycle, ping-pong, offset, continue). Both run on Windows and Mac.
• What else comes in the plan: the mouse app with its three wheels, all 22 extensions, both Tool wheels and, on Windows, the After Effects and Premiere Pro workspaces. The workspaces, captions, Retakes, cloud sync and in-app updates are Windows only.
• Price: $25 a month, $249 a year, or $499 once for one of the first 100 lifetime keys. See pricing.
• Trial: 3 days, no card, and every After Effects tool works fully. One trial per person and per computer.

Questions people ask

Sources

Checked on 2026-11-03. Prices and features change: each link goes to the maker's own page.

1. Adobe After Effects product page: single-app price and plan inclusions (checked 3 Nov 2026)
2. Adobe Creative Cloud plans, India: After Effects price incl. GST (checked 3 Nov 2026)
3. Adobe After Effects free trial: platforms and Creative Cloud membership (checked 3 Nov 2026)
4. Adobe After Effects expression language reference

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