BPHYS File

What are BPHYS files and how to open them

Are you having problems opening a BPHYS file or are you simply curious about its contents? We're here to explain the properties of these files and provide you with software that can open or handle your BPHYS files.

What is a BPHYS file?

A .BPHYS file is a Blender Physics External Cache file.

Blender writes these files to store the results of physics simulations separately on disk, so that once simulations are baked, Blender can load their state from file rather than recalculating everything each time. These "external cache" files are produced when a physics simulation object has "Disk Cache" enabled with "External" path set.

They are generated per frame (often one file for each simulation frame) and are used when playing back or rendering animations involving particles, cloth, soft bodies, smoke, rigid bodies, or dynamic paint. Blender names these files according to a pattern that includes the cache name, the frame number, and an index. They are stored in a folder alongside or near the main .blend file, usually in a directory named starting with "blendcache_".

Technically the file begins with an ASCII signature "BPHYSICS" at byte offset 0, followed by a 32-bit unsigned integer that encodes the simulation type (e.g. particles, cloth, etc.) and flags defining which data streams are included (such as location, velocity, rotation, angular velocity, size, timing, and optional boid behaviour). Then there is a count of data points or particles, followed by that many records, each containing the fields in a fixed order.

Byte signatures: bytes 0-7 equal ASCII "BPHYSICS" at offset 0.

How to open BPHYS files

Important: Different programs may use files with the BPHYS file extension for different purposes, so unless you are sure which format your BPHYS file is, you may need to try a few different programs.

We have not yet verified any programs for Windows that work with this specific file format. If you know one, please use the 'Suggest a program' link below. Thanks!

Last updated: August 24, 2026

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