> For the complete documentation index, see [llms.txt](https://tk233.gitbook.io/notes/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://tk233.gitbook.io/notes/ml-rl/notes-on-urdf-and-mjcf.md).

# Notes on URDF and MJCF

It is important to note the slight differences between the URDF and MJCF formats to avoid bugs. In this writeup I will try to list down some common pitfalls on working with these two formats.

### Box size

URDF defines a box size with the three side lengths, while MJCF specifies **half-size** length.

<figure><img src="/files/cEEP8LAulLqvKmndKamC" alt=""><figcaption></figcaption></figure>