NASA TLX Welcome to the NASA-TLX homepage. NASA-TLX is a subjective workload assessment tool. NASA-TLX allows users to perform subjective workload assessments on operator(s) working with various human-machine systems. NASA-TLX is a multi-dimensional rating procedure that derives an overall workload score based on a weighted average of ratings on six subscales. in Human Factorswith assesmenthf Note: Bookmarks for CMPE 248, Spring 08