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TLX Left-Side Header Image
Mission Statement Header
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 Download Header
Click to download the Official NASA TLX iOS App from the Apple App Store

NASA TLX iOS App User Guide (PDF Format - 1.4MB)
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NASA TLX: Task Load Index Overview Header
The Official NASA Task Load Index (TLX) is a subjective workload assessment tool to allow users to perform subjective workload asessments on operator(s) working with various human-machine interface systems. Originally developed as a paper and pencil questionnaire by NASA Ames Research Center’s (ARC) Sandra Hart in the 1980s, NASA TLX has become the gold standard for measuring subjective workload across a wide range of applications.

By incorporating a multi-dimensional rating procedure, NASA TLX derives an overall workload score based on a weighted average of ratings on six subscales:

- Mental Demand
- Physical Demand
- Temporal Demand
- Performance
- Effort
- Frustration

NASA TLX has been successfully used around the world to assess workload in various environments such as aircraft cockpits; command, control, and communication (C3) workstations; supervisory and process control; and simulations and laboratory tests.

Current Version

The Official NASA TLX continues to be available as a paper and pencil version in PDF format, which also contains background information and a user manual for its use.

TLX Mobile App

To meet a growing demand for the Official NASA TLX, it is now available as a brand new mobile app on the App Store for iPhone, iPad, and iPod touch. Click the button on the left side of this page to download the app. Additionally, NASA TLX will soon be available for the Mac on the Mac App Store.

Other Resources

Additionally, access to NASA TLX publications is available to provide insight into how NASA TLX has been applied in a variety of research applications. If you have used NASA TLX and would like to add to our publications database, please contact us.
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Curator: Phil So
NASA Official: Brian Gore
Last Updated: February 15, 2017