System Usability Scale (SUS)

What is the System Usability Scale (SUS)?

The System Usability Scale is a rapid and reliable tool for measuring a combination of factors, including:

Example SUS questionnaire
⏱ Efficiency: How fast someone can use it
🧠 Intuitiveness: How effortlessly someone can understand it
🎯 Ease: How simple it is to use
😀 Satisfaction: How much a user subjectively likes or dislikes using it

It was originally created in 1986, and it’s effectiveness is supported by academic research due to it’s:
✅ Validity - it actually measures what it intends to measure
✅ Reliability - users consistently answer the questions in the same way
✅ Sensitivity - it can detect meaningful differences

Scales with high validity such as the SUS, produce more trustworthy results which brings about well-informed decision making. Additionally, there is a large amount of industry-wide data available to help benchmark a product’s score and understand it in the context of competitors.

The SUS consists of 10 Likert-scale questions and produces a score from 0 - 100. Extensive benchmarking of SUS scores has been conducted by researchers on many different systems and an average SUS score of 68 across 500 studies has been found. A score of 80 or higher indicates high usability. To put it simply, the higher the SUS score, the better the usability of a system.