[UE5] Animation Retargeting Basics: Moving a Mixamo Run onto Manny

You found a run cycle on Mixamo and want to use it in your own game. It imports into UE fine, but it never appears as an option in Manny's Animation Blueprint. When that happens, check whether the animation is driving a different skeleton than you expect.

Even between two humanoid models, the bone names, bone counts, and the pose the arms rest in can all differ. Reconciling those differences to move motion onto a different character is what retargeting means.

In this article we move a Mixamo run onto Manny, UE5's mannequin. The goal is to export one Animation Sequence for Manny that plays the run when you open it.

What You'll Learn

• How to import a model and an animation onto the correct skeleton each
• How IK Rig defines body parts and IK Retargeter maps motion between them
• How to align the arms' reference pose and export the converted result
• What to check, and in what order, when arms clip or feet slide

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What exactly gets mapped?

A character's arm moves because the bones running from shoulder to hand rotate. Rotate the upper arm bone and the forearm and hand below it follow. The collection of bone names and their parent-child relationships is the Skeleton.

In UE, the character's visible mesh that deforms with those bones is a Skeletal Mesh, and a single recorded motion such as a run or a jump is an Animation Sequence. An animation stores changes like "rotate the left upper arm this way," and it is bound to a specific Skeleton.

Mixamo and Manny do not share that Skeleton. The left upper arm, for example, is called LeftArm in Mixamo and upperarm_l in Manny. Passing the motion across takes more than renaming: bone orientation and connectivity matter too.

That is what chains are for. Register "upper arm through hand" as one left arm, and left-arm motion maps onto the left arm even though the bone names differ.

Asset	Its role in this article
IK Rig	Defines chains such as left arm and right leg, plus the pelvis, on one skeleton
IK Retargeter	Uses two IK Rigs to map body parts and convert the motion

Think of an IK Rig as one character's map of body parts and an IK Retargeter as the part that reads two maps and hands the motion across, and it becomes easier to keep track of what you are building.

From here on, the Mixamo side that sends the motion is the Source, and the Manny side that receives it is the Target.

Not every pair of characters needs retargeting. Models that share a Skeleton can often share animation assets directly. Here we deal with Mixamo and Manny, which have different skeletons.

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Prepare the Mixamo model and run

From here we use a Third Person project that contains Manny's Skeletal Mesh SKM_Manny. Menu names follow UE5.6's English UI. Older versions differ in places; for example "Set Pelvis" below appears as "Set Retarget Root."

1. Get the model and the animation from the same character

Sign in to Mixamo with an Adobe ID and pick one humanoid character. To start, use a model in a T-pose with the arms out to the sides, plus a run for that same character.

Choose FBX as the download format. FBX is a file format for passing 3D models, skeletons, and animation between applications.

FBX to prepare	Contents	Settings to choose
Character	Mesh and skeleton	Download the T-pose model with its mesh (choose "With Skin" if the option appears)
A run such as Running	Motion on the same skeleton	Choose "In Place" and download "Without Skin"

In Place means the feet move but the character stays put. This article prepares "what running looks like," and leaves moving forward in the game to Character Movement later. Avoid motions with no In Place option and practice with a run that offers one.

The important part is to not change the selected character between downloading the model and downloading the run. Mixing in a run built for a different character breaks the skeleton on import, before retargeting even starts.

2. Import the model first

Create the folder Animations/RetargetPractice/Source in the UE content browser and import the model's FBX. When the "Interchange Pipeline Configuration" import dialog opens, check the following.

Setting	Value	Reason
Import Skeletal Meshes	On	Import it as a model driven by bones
Skeleton	Unspecified	Create a new Skeleton on the Mixamo side
Import Only Animations	Off	Right now we import the mesh and skeleton
Import Animations	Off	The run comes from a separate FBX

Rename the generated Skeletal Mesh to SK_Mixamo and the Skeleton to SKEL_Mixamo. These names exist purely so you can tell them apart in the steps ahead; the auto-generated names vary by file.

Open SK_Mixamo and confirm the model displays and that the bone list contains names corresponding to Hips and LeftArm. A prefix such as mixamorig on the bone names is fine as is.

3. Import the run onto the same Skeleton

Next, import the run's FBX into the same folder.

Setting	Value
Import Only Animations	On
Skeleton	The SKEL_Mixamo from before
Import Animations	On

If your environment opens the older "FBX Import Options" instead, use "Skeletal Mesh" for the model import, and for the run turn "Import Mesh" off and specify the same Skeleton. Either way, the point is the same: do not choose Manny's Skeleton as the destination for the run.

Rename the generated Animation Sequence to A_Mixamo_Run and open it. If the Mixamo character runs in place, you are ready. If the pose collapses here, do not move on to the conversion settings; check the character you downloaded and the Skeleton you imported onto.

You can also try automatic conversion first

In UE5.6 you can right-click A_Mixamo_Run, open "Retarget Animation Assets," and set "Target Preview Mesh" to SKM_Manny. A Preview Mesh is the model shown on screen so you can see the converted result. With "Auto Generate Retargeter" on, UE builds the skeleton mapping for you.

If the preview looks good, "Export Animations" writes it out. Use "Export Retarget Assets" when you also want the IK Rig and IK Retargeter for further tuning. Automatic recognition depends on the skeleton, so confirm the arms and legs move naturally before you adopt the result.

Below we build our own practice IK Rigs, so you understand the mapping and can fix the places automatic conversion gets wrong. Keep them separate from any auto-generated assets.

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IK Rig: define body parts on each skeleton

First, create one IK Rig for the Source and one for the Target. Save them to Animations/RetargetPractice/Rigs.

1. In the content browser choose "Add" → "Animation" → "IK Rig" → "IK Rig."
2. Pick SK_Mixamo as the Skeletal Mesh and name it IK_Mixamo.
3. Repeat with SKM_Manny and create IK_Manny_Practice.

Rather than using the IK Rig bundled with the template, create both fresh for practice so the chains you are about to register line up.

Set the pelvis bone

Open IK_Mixamo, right-click the bone corresponding to Hips in the "Hierarchy" list, and choose "Set Pelvis." Do the same on pelvis in IK_Manny_Practice.

The Pelvis is the hips. It is the reference for transferring the up-and-down hip motion of a run in a way that suits each character's build. Set the hip bone pelvis, not Manny's root.

Create chains for arms, legs, spine, and head

In the "IK Retargeting" panel, use "Add New Chain (+)" to create a chain and specify its name plus its start and end bones. For an arm that is "upper arm through hand." Bones traced through the parent-child hierarchy between start and end are included in the chain.

To begin, create these six with identical chain names in both IK Rigs.

Chain Name	Mixamo Start Bone → End Bone	Manny Start Bone → End Bone
Spine	Spine → Spine2	spine_01 → spine_05
Head	Neck → Head	neck_01 → head
LeftArm	LeftArm → LeftHand	upperarm_l → hand_l
RightArm	RightArm → RightHand	upperarm_r → hand_r
LeftLeg	LeftUpLeg → LeftToeBase	thigh_l → ball_l
RightLeg	RightUpLeg → RightToeBase	thigh_r → ball_r

The Mixamo column omits the bone-name prefix. Pick the matching bone from the actual list. The ToeBase / ball bones are the joints at the base of the toes where the foot bends. On models with a different bone layout, do not decide by name alone; select the bone in the list and confirm where it sits.

Left and Right here mean the character's own left and right, which is the reverse of left and right on screen when viewed from the front.

These six chains are enough to transfer a rough full-body run. Add clavicle and finger detail after you have confirmed the run comes across.

The IK in IK Rig refers to matching hand and foot tips to a goal position. But to transfer the basic motion, the "IK Goal" that represents that position is not required. We skip it here and save both IK Rigs with just chains and the pelvis set.

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IK Retargeter: connect source and target

With two maps of body parts in hand, the IK Retargeter combines them.

1. In the content browser choose "Add" → "Animation" → "IK Rig" → "IK Retargeter."
2. Choose IK_Mixamo as the Source IK Rig and name it RTG_Mixamo_To_Manny.
3. In the window that opens, select "Asset Settings" and set the Target IK Rig to IK_Manny_Practice.
4. Confirm the Source Preview Mesh is SK_Mixamo and the Target Preview Mesh is SKM_Manny.

Check that the IK Rig and the displayed model line up correctly on both the Source and Target sides.

Transfer the hip motion, then the body parts

The Op Stack in UE5.6 is the list of operations used for the conversion, run from the top down. Start with just the two basics: "move the hips" and "move the arms and legs."

Operation	Role
Pelvis Motion	Moves the designated hip motion from Source to Target
FK Chains	Transfers bone rotations per chain to build the arm and leg poses

Put those two in the Op Stack in that order. Use them if they are already in the default list; add them from "Add New Op" if not. In this practice asset, remove everything else such as IK correction and Root Motion, so you can see the basic conversion result first.

FK builds the pose by following the bone chain from upper arm to forearm to hand. Using the chains you just registered, it hands one arm's bend across to the other arm.

Confirm the chain mapping

Select "FK Chains" in the Op Stack and the Details panel shows the chain mapping and conversion settings. Confirm the Target IK Rig is IK_Manny_Practice and set each Target Chain's Source Chain to the one with the same name.

For example, assign Source LeftArm to Target LeftArm, and RightLeg to RightLeg. If all six rows have a mapping and left and right are not swapped, you are good.

Using Auto-Map is fine too. It can also look for similar names, so exact matching is not the only rule. We aligned the names here to make the candidates easy to compare and mismatches easy to spot.

In older UE versions the mapping table lives in a separate "Chain Mapping" panel. Whichever screen you are on, what you are confirming is the same: "which source body part feeds this target body part?"

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Align the arms with a retarget pose

Even with the left arm mapped to the left arm, a mismatch in the starting pose leaves the arms riding too high or pulled in toward the body. That is what the retarget pose — the reference pose used while transferring motion — is for.

Our Source is a T-pose with the arms out to the sides. Manny, by contrast, uses an A-pose with the arms angled down. Leave that difference in place and "how far the arms moved from the reference" cannot be received consistently.

Here we leave the Source alone and bring the Target's reference pose closer to a T-pose.

1. Switch the IK Retargeter display to "Show Retarget Pose" and set the edit target to "Target."
2. From the pose "Create (+)" → "Create," make a new pose called T_FromMixamo. Keeping the original Default pose lets you compare and start over.
3. Confirm T_FromMixamo is selected and enter pose edit mode. Select Manny's upperarm_l in the Hierarchy and use the rotation handle to raise the arm until it matches the source's left upper arm.
4. Do the same for upperarm_r. Look from the side as well as the front and confirm the elbows and wrists are not twisted unnaturally.
5. Finish editing and return to "Run Retarget." Remember to save.

What you are matching is bone orientation, not body silhouette. Arm lengths and chest thickness differ, so there is no need to force the two characters' hands into the same spot. The rotation angle also varies by model, so rather than fixing a number for both arms, adjust while watching the display.

This edit does not rewrite the motion in A_Mixamo_Run. It changes the reference this Retargeter uses when transferring motion, which changes the converted result on Manny's side.

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Check the run and export an asset for Manny

Watch one loop in the preview first

Double-click A_Mixamo_Run in the IK Retargeter's "Asset Browser" and play it with "Run Retarget." If the Target moves along with the Source's run, the body-part mapping is working.

Pause and scrub back and forth, and look for the following.

• Are the arms and legs swapped left to right?
• Do the elbows or knees bend in an unnatural direction?
• Does the torso follow the hips as they rise and fall?
• Are there breakdowns such as arms sinking deep into the chest or feet floating well off the ground?

At this stage the clip is In Place, so running on the spot without moving forward is exactly what you should see. Confirm the full-body motion transferred first; fine ground-contact work comes later.

Save it as an Animation Sequence

The preview only shows the converted result — no asset for Manny exists yet. The following steps export one.

1. Select A_Mixamo_Run in the Asset Browser and press "Export Selected Animations."
2. Choose Animations/RetargetPractice/Retargeted as the destination.
3. Use Prefix or Suffix to distinguish the result from the original, then run Export.
4. Rename the generated Animation Sequence to A_Manny_Run and open it.

If the exported asset plays Manny running on its own, and its Skeleton is Manny's, it worked. The original Mixamo asset and the converted Manny asset now exist separately.

If you are unsure which Skeleton an asset uses, hover over A_Manny_Run in the content browser and check the Skeleton shown in the asset tooltip. Compare it against the Skeleton on the SKM_Manny side.

This A_Manny_Run is now selectable in any Animation Blueprint or Blend Space that uses Manny's Skeleton. For playing it back based on speed in game, continue to Animation Blueprint Basics.

Fix the pose and you have to export again. An exported Sequence is an independent asset that stored the conversion result at that moment. Fixing only the Retargeter leaves the existing A_Manny_Run unchanged. Export under a different name to compare before and after.

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Common Pitfalls

First narrow down where it breaks: the original Mixamo asset, the Retargeter preview, or the exported Manny asset. If the original is already broken, check the import; if only the preview is broken, check the mapping and pose; if only the exported asset is stale, check whether you re-exported.

Symptom	Where to look first
The source animation isn't in the list	Is the source IK Rig and Preview Mesh on the Mixamo side? Is the run's Skeleton SKEL_Mixamo?
Arms or legs don't move / are swapped	Are any FK Chains mappings blank? Are Left/Right and each chain's start and end correct?
Hips don't move / torso height looks wrong	Did you set the pelvis on both IK Rigs? Is Pelvis Motion using that pelvis?
Arms clip into the body / shoulders ride high	Check the arm chains, then compare arm orientation in the retarget pose
Preview is fixed but the game shows old motion	Did you re-export? Is the Animation Blueprint using the new Sequence?
It only runs in place	That is correct here. Forward movement in game comes from Character Movement

Foot sliding needs different investigation depending on where it happens

Foot sliding is when a foot that should be planted appears to slide across the ground. Do not assume leg length is the cause; check in this order.

1. Unnatural before conversion: check the original motion and the import.
2. Feet float or sink in the converted preview: check the leg chains, the reference pose, and the pelvis assignment. Consider extra ground-contact correction when the builds differ a lot.
3. Slides only when moving forward in game: check whether Character Movement's speed matches the animation's stride and playback rate.

In an in-place preview it is natural for a planted foot to travel backward relative to the body. Rather than trying to pin every In Place footfall to the same spot on the floor, also check how it looks once forward movement is combined in game.

Speed Planting is an extra feature for stabilizing planted feet. It needs a curve (a value that changes over time) recording foot speed in the original animation, plus an IK Goal and an IK Solver to match the leg to it. Get the basic conversion working first, then move on to Epic's foot-sliding guide — the reason for each addition will be clearer.

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Bonus: Extending to more animations

Motion on the same skeleton can reuse the setup

RTG_Mixamo_To_Manny is reusable for the same Source and Target pair. When you next bring in a walk or an idle, align the Source Skeleton and the same mapping converts it.

That said, a setup that is clean on a run can put the arm through the chest on a big attack swing. Check a few clips first, and once they look right, multi-select in the Asset Browser and export them together.

Add fingers and shoulders when the motion calls for it

The six chains here cover basic full-body motion. If you need expression such as a closing fist or a big shoulder shrug, add finger or clavicle chains to both IK Rigs and map them. Bones with no mapping will not necessarily reproduce the original fine detail.

Root Motion is for when you want the animation to drive forward movement too

Root Motion drives the character's position and orientation from root movement recorded in the animation. Compared with this article's "in-place run + Character Movement," it changes which side is responsible for moving forward.

Mixamo skeletons often make the hip bone Hips the top of the hierarchy, unlike Manny's layout with a root separate from the pelvis. UE's Root Motion conversion operations include a way to derive root motion from hip motion, but it requires source motion that includes translation plus extra configuration. Start with the In Place case here to get a feel for cross-skeleton conversion, and it will be easier to organize.

When you want a much larger library of locomotion, Motion Matching and the Game Animation Sample is a natural next step. The way of looking at it that you learned here — which skeleton's motion goes to which skeleton — carries over.

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Summary

Retargeting is the work of moving motion authored for one skeleton onto your own character. IK Rig defines each skeleton's body parts, IK Retargeter connects the mapping, and after aligning the reference pose you export a new Animation Sequence.

Start with a single run and confirm the chain: the original asset plays → the target moves → the exported asset plays on its own. Once the assets are in place, the next stage is playing that run back in response to input and speed in game.

Further Reading

• IK Rig Retargeting (Epic, UE5.6)
• Auto Retargeting (Epic, UE5.6)
• Interchange Import Reference (Epic, UE5.6)
• Retargeting Operation Stack (Epic)

To extend into falling and collapsing, continue to Physics Assets and Ragdolls.