The System Usability Scale (SUS) block measures how usable participants found your product, using the ten standard SUS statements. Participants rate each statement on a five-point agreement scale, and Askable turns their answers into a single score out of 100, along with a grade, an adjective rating and an acceptability verdict.
SUS is one of the most widely used usability questionnaires in the world. Because every study uses the same statements and the same scale, your score can be compared with published benchmarks, with your competitors, and with your own earlier rounds of testing.
When to use SUS
SUS works best straight after participants have used the thing you're measuring. A common pattern is to add a SUS block directly after a Prototype test, Live website test or Live mobile test block, so the experience is fresh in participants' minds. You can also use it on its own in a survey to benchmark a product participants already use.
Using SUS in a Variant Comparison
SUS blocks can be added inside a Variant Comparison, which makes it easy to find out which of two or more designs participants find more usable. Add a SUS block to each variant, straight after the task participants complete in that variant. Then create a results comparison to see each variant's SUS score side by side.
If you're using an alternating comparison, where each participant sees every variant, a SUS block in each variant means every participant rates each design separately.
Setting up your SUS block
Click "Add block" and choose "System Usability Scale".
What are participants rating?
This is the only part of the SUS block you can change. Choose the word that best describes what participants are rating:
system
app
website
product
platform
tool
service
dashboard
prototype
The word you choose is used in all ten statements, so "I thought the system was easy to use" becomes "I thought the website was easy to use". The participant preview beside the editor updates to show exactly what participants will read.
The ten statements
Every SUS block uses the same ten statements, shown here with "system" as the subject:
I think that I would like to use this system frequently
I found the system unnecessarily complex
I thought the system was easy to use
I think that I would need the support of a technical person to be able to use this system
I found the various functions in this system were well integrated
I thought there was too much inconsistency in this system
I would imagine that most people would learn to use this system very quickly
I found the system very cumbersome to use
I felt very confident using the system
I needed to learn a lot of things before I could get going with this system
You'll notice the statements alternate between positive (odd numbers) and negative (even numbers). This is deliberate: it stops participants from simply agreeing with everything, and it's built into how the score is calculated.
Scale
Participants rate each statement on a five-point agreement scale: Strongly disagree, Disagree, Neutral, Agree, Strongly agree.
Why can't I edit the statements or the scale? A SUS score only means something if it's collected the standard way. Changing the wording, the number of scale points or the order of the statements would make your score impossible to compare with anyone else's. For the same reason, there's no option to randomise the order or add an N/A answer. If you want to ask your own set of rating statements, use a Matrix block instead.
Question and additional info
Your SUS block starts with the question "Thinking about your experience, how much do you agree with each statement?" You can edit this to set the context for participants, for example "Thinking about the checkout you just used, how much do you agree with each statement?"
Adding Context
Use the "Additional info" field to give participants any extra context they need, such as reminding them which part of the product to think about. Avoid anything that might lead them towards a particular answer.
