Phys Bones | VRC Avatars for Dummies
PhysBones are VRChat components that add secondary motion to avatar parts such as hair, ears, tails, loose clothing, straps, chains, or accessories. They can also be grabbed, posed, or collided with when the avatar and user permissions allow it.
Use them after the base avatar uploads cleanly. PhysBones are fun, but they touch performance, interaction settings, colliders, and sometimes animator logic, so it is worth building the first chain slowly.
Creator: DedZedOffishal
Use the video for the Unity setup, then follow the checklist below for tuning and testing before adding PhysBones everywhere.
Make one small PhysBone chain feel good before copying the pattern to the rest of the avatar.
- Pick one part, such as hair tips, one tail chain, or one accessory.
- Add and tune one
VRCPhysBonecomponent on the correct bone chain. - Test motion, grabbing, collision, and performance in VRChat before expanding.
PhysBones are part of Avatar Components. They can be affected by other users if your interaction settings allow it, and they contribute to avatar performance rank through component, transform, collider, and collision-check counts.
When To Use PhysBones
PhysBones are a good fit when a part should move after the avatar moves:
- hair strands, bangs, ponytails, or braids
- ears, tails, wings, ribbons, or charms
- soft clothing pieces, belts, straps, or sleeves
- accessories that should sway or react naturally
- grab-and-pose parts that are meant to be interactive
Do not add them just because a part exists. A rigid belt buckle, button, or tiny accessory may look better, cost less, and cause fewer bugs if it stays static.
Before You Start
Have these ready:
- a working private upload of the avatar
- clean bone names for the moving part
- a backup before editing the armature or prefab
- no red Unity Console errors
- a clear decision about whether the part should be grabbable, poseable, collidable, or only animated
If the model has messy bones or unclear hierarchy, clean that up first. PhysBone tuning is much easier when you know exactly which transforms the component affects.
Basic Build Order
- Pick one bone chain or transform group.
- Add a
VRCPhysBonecomponent to the intended root object. - Confirm the affected transforms are the ones you expect.
- Tune pull, spring, stiffness, gravity, and limits in small changes.
- Add colliders only when the motion actually needs collision.
- Decide whether grabbing or posing should be allowed.
- Enter Play mode or use SDK/debug tools to preview the behavior.
- Upload privately and test in VRChat.
- Check avatar performance stats before repeating the setup.
Keep the first pass conservative. Big motion, lots of colliders, and many affected transforms can make an avatar feel noisy and expensive.
Tuning Guide
| Setting area | What it affects | Beginner advice |
|---|---|---|
| Affected transforms | Which bones PhysBones move | Keep the chain short until it behaves. |
| Pull and spring | How strongly the chain returns or bounces | Increase gradually and test while moving. |
| Limits | How far the chain can rotate or stretch | Use limits to stop clipping and wild motion. |
| Gravity | Directional pull on the chain | Useful for tails, hair, and hanging pieces. |
| Collision | Interaction with PhysBone colliders | Add only the colliders you need. |
| Grabbing and posing | Whether users can hold or pose the part | Leave off unless the interaction is intentional. |
Performance Checks
VRChat's performance ranking looks at PhysBone component count, affected transforms, colliders, and collision checks. That means a few carefully tuned PhysBones are usually healthier than many broad components that affect every little decorative bone.
Check:
- how many PhysBone components the avatar has
- how many transforms are affected
- whether colliders are duplicated or oversized
- whether Quest, Android, or iOS versions need a simpler setup
- whether disabled objects still leave components counted by the SDK
Common Problems
Help! The part swings too far or clips through the body.
Tighten limits, reduce overly loose motion, and test while walking, turning, crouching, and using gestures. Static scene preview is not enough.
Help! Nothing moves.
Check that the component is on the correct transform, the affected chain is not empty, and the bones are not being held rigid by another animator or constraint setup.
Help! Other people cannot grab it.
Confirm the PhysBone allows the interaction you want, then test VRChat's avatar interaction permissions. User settings can affect whether other people can interact with your PhysBones.
Help! The avatar performance rank got worse.
Reduce affected transforms, remove unnecessary colliders, merge or simplify similar chains, and avoid putting PhysBones on tiny details that do not change the avatar's silhouette.
Official References
- VRChat PhysBones
- VRChat Avatar Components
- VRChat Debugging Avatar Components
- VRChat Avatar Performance Ranks
- VRChat Avatar Impostors
PhysBone setup advice here is practical guidance layered on top of VRChat's official component behavior. Exact limits, component options, and platform behavior should be checked in the official PhysBones and performance-rank pages before upload.
Related Resources
- VRChat PhysBones
- VRChat Avatar Components
- VRChat Debugging Avatar Components
- VRChat Avatar Performance Ranking System
- Toggling Phys Bones
- Avatar Optimization Checklist
Final Advice
PhysBones are best when they are intentional. Add them to parts that should genuinely feel alive, tune them in motion, and keep performance visible while you work.
Topics: Phys Bones, VRChat avatars, avatar workflow
Keep PhysBones Fun Without Hiding The Avatar
Tune PhysBone motion while keeping performance rank, mobile limits, and impostor visibility in mind.
Suggested Order
- Tune one chain first Make one hair, tail, ear, or accessory chain feel good before copying settings across the avatar.
- Watch performance rank PhysBone components, transforms, colliders, contacts, and collision checks all contribute to avatar performance.
- Plan mobile visibility If Quest or Android matters, keep mobile component limits and avatar impostors in mind before publishing.
Related VRCreators Guides
- Avatar Optimization Checklist Use this to reduce materials, components, texture cost, and performance rank issues.
- Avatar Impostors And Performance Use this when your avatar may be hidden or replaced for other players.
- Quest Compatibility Checklist Use this before promising a mobile-friendly avatar.
Common Questions
Do disabled PhysBones count for performance?
VRChat performance rank can count avatar components and GameObjects even when they are disabled, so test the actual uploaded avatar stats.
Should every moving accessory use PhysBones?
No. Use PhysBones where motion improves the avatar. Static or rarely noticed details are often better left simple.
