This is a good tutorial video showing how the Amputee Mobility Predictor tests with a prosthesis (AMPPRO) and without a prosthesis (AMPnoPRO) are performed in the US, to assess the activity level - or K-level - of a person with lower limb amputation. The tests are easy enough to perform at home with the help of a third party, if you want to assess yourself.

The supporting documents and forms for the AMPPRO and AMPnoPRO can be downloaded here.