Free tool

The System Usability Scale (SUS) calculator.

Turn ten questionnaire answers into a SUS score, a grade, and a percentile. Paste from a spreadsheet or type into the grid, with live charts and nothing leaving your browser.

What is a good SUS score?

Sixty-eight is the average product, so anything above it beats the middle of the pack. Eighty is the goal most teams aim for: an A minus, better than about 85% of products measured. Below 52 lands an F, the bottom 15%. Type your answers below and the calculator grades your score against that same scale.

The answers below are placeholders. Replace them with your own, either by typing straight into the grid or by pasting data in the format described underneath.

How the scoring works

1 to 5:: 1 means strongly disagree, 5 means strongly agree. Click a box and type, or paste rows below.
All 10 to count:: a respondent only scores once every statement has an answer. Half finished rows sit out.
Mixed tones:: odd statements praise the product, even ones criticise it. That flip is deliberate, and the calculator reverses the even ones before scoring.

The ten statements, in order.

Paste or type answers in this order, S1 down to S10. Running this for real? Swap “this system” for your product’s name.

S1 I think that I would like to use this system frequently.
S2 I found the system unnecessarily complex.
S3 I thought the system was easy to use.
S4 I think that I would need the support of a technical person to be able to use this system.
S5 I found the various functions in this system were well integrated.
S6 I thought there was too much inconsistency in this system.
S7 I would imagine that most people would learn to use this system very quickly.
S8 I found the system very cumbersome to use.
S9 I felt very confident using the system.
S10 I needed to learn a lot of things before I could get going with this system.

Paste answers from a spreadsheet

One respondent per line, ten numbers from 1 to 5 in statement order S1 to S10. Separate the numbers with tabs, commas, or spaces, so a spreadsheet row pastes straight in. Rows that do not fit the format are skipped and reported, never silently dropped.

The grid. Type here, or proofread a paste.

SUS answers per respondent for statements 1 to 10, with each respondent scored
Who	S1	S2	S3	S4	S5	S6	S7	S8	S9	S10	Score
R1	Respondent 1, statement 1	Respondent 1, statement 2	Respondent 1, statement 3	Respondent 1, statement 4	Respondent 1, statement 5	Respondent 1, statement 6	Respondent 1, statement 7	Respondent 1, statement 8	Respondent 1, statement 9	Respondent 1, statement 10	75
R2	Respondent 2, statement 1	Respondent 2, statement 2	Respondent 2, statement 3	Respondent 2, statement 4	Respondent 2, statement 5	Respondent 2, statement 6	Respondent 2, statement 7	Respondent 2, statement 8	Respondent 2, statement 9	Respondent 2, statement 10	92.5
R3	Respondent 3, statement 1	Respondent 3, statement 2	Respondent 3, statement 3	Respondent 3, statement 4	Respondent 3, statement 5	Respondent 3, statement 6	Respondent 3, statement 7	Respondent 3, statement 8	Respondent 3, statement 9	Respondent 3, statement 10	60

Mean SUS

75.8

3 of 3 complete

Grade

70-79th percentile band

Against average

+7.8

points vs the average product (68)

The 95% range runs 35.4 to 100. Small samples wobble: each extra respondent tightens it. The range stays inside 0 to 100 because scores cannot leave it.

Every complete respondent scored, against the average product at 68and your mean at 75.8. Short bars are not failures, they are the spread your range is built from.

Everything runs in your browser. Nothing you type leaves your device.

Rule of thumb: 68 is average, 80 is the goal.

Sixty-eight sits at the 50th percentile, a solid C. Eighty marks an A minus and has become the common industrial goal: attainable, but only about one product in seven gets there. Below 52 is an F. The calculator pins your score to this scale live.

How is a SUS score actually calculated?

Each statement takes an answer from 1 to 5. Odd statements praise the product, so they contribute the answer minus one. Even statements criticise it, so they contribute five minus the answer. Add the ten contributions, multiply by 2.5, and the result sits on a 0 to 100 scale. The grid above does every step live.

That recipe comes from Brooke (1996), who designed the ten statements to alternate in tone on purpose. The benchmarks around it, the 68 average and the curved grading scale, come from Sauro and Lewis (2016), built on thousands of published scores. Sauro’s own guide walks through what each grade means in practice.

The words, in plain English.

SUS score: A 0 to 100 rating of perceived usability from ten questionnaire answers. It is not a percentage: 68 is average, not 68% of anything.
Grade: A letter from A+ to F pinned to the curved scale of Lewis and Sauro. C means average, F starts below 52, and each grade maps to a percentile band.
Percentile band: Where your score sits against thousands of published SUS scores. The 70 to 79 band means your product beats roughly that share of everything measured.
95% range: The spread your true average plausibly sits in, built from your spread and headcount with the t distribution. More respondents, narrower range.
Straight-liner: A respondent who ticks the same answer throughout, fives for praise and fives for criticism in one breath. The grid flags these rows for a second look.

How many people need to answer?

SUS answers get counted, not just read, so treat this like survey maths: tiny samples wobble hard. Three respondents can swing the range forty points either way, as the seed data shows. Keep adding people and watch the range tighten. Small is fine. Unreported uncertainty is not.

When the question is finding problems rather than scoring them, five users per round is the classic setup, see the usability sample size calculator. When the question is how many responses a survey needs, reach for the survey sample size calculator instead. Scoring and finding are different jobs.

Why do half the statements sound negative?

It is a trap for autopilot answers. Five statements praise, five criticise, so anyone ticking straight fives contradicts themselves in the same breath. The calculator reverses the negative ones before scoring, which also flags straight liners in the grid. Genuine opinions survive the flip. Lazy ones cancel out.

That alternating tone is why the questionnaire takes under five minutes yet still catches careless responses, a neat piece of design that has held up for decades. If you are planning the study around the score, survey work here pairs the questionnaire with analysis, and the quick guide to UX research shows where SUS fits among other methods.

FAQs

Questions the calculator gets asked.

One respondent per line, ten whole numbers from 1 to 5 in statement order S1 to S10. Tabs, commas, or spaces all work, so spreadsheet rows paste straight in. Rows that break the format are skipped and named in the report, and pasting appends to the grid, which tops out at twenty respondents.

Their row sits out of every number until all ten boxes hold an answer. SUS scoring needs the full set: nine answers cannot scale to 100. The grid marks these rows plainly, so partial data never quietly warps the mean.

Yes, but keep the alternating tones intact: odd statements praise, even statements criticise. Swap “this system” for your product name freely. Rewording beyond that breaks comparability with the 68 benchmark, which was built on the standard wording (Brooke, 1996).

Each statement contributes 0 to 4 points, the ten sum to at most 40, and scaling by 2.5 lands single scores on 2.5-point steps. Averaging across respondents then splits those steps further. Decimals mean the maths ran, not that it broke.

No. All the maths runs in your browser on your device. Nothing you enter is transmitted, stored, or logged, which keeps the tool comfortable to use under POPIA.

Calculator reviewed October 2026.

Where do these numbers come from?

Every figure on this page traces to one of the sources below, cited Harvard style. Nothing here is agency folklore.

Brooke, J. (1996) ‘SUS: a “quick and dirty” usability scale’. In: Jordan, P.W., Thomas, B., Weerdmeester, B.A. and McClelland, I.L. (eds.) Usability Evaluation in Industry. London: Taylor & Francis, pp. 189–194.
Lewis, J.R. and Sauro, J. (2018) ‘Item benchmarks for the System Usability Scale’, Journal of Usability Studies, 13(3), pp. 158–167. Available at: https://dl.acm.org/doi/10.5555/3294033.3294037 (Accessed: 12 October 2026).
Sauro, J. (n.d.) ‘Measuring usability with the System Usability Scale (SUS)’, MeasuringU. Available at: https://measuringu.com/sus/ (Accessed: 12 October 2026).
Sauro, J. (2018) ‘5 ways to interpret a SUS score’, MeasuringU, 19 September. Available at: https://measuringu.com/interpret-sus-score/ (Accessed: 12 October 2026).
Sauro, J. and Lewis, J.R. (2016) Quantifying the User Experience: Practical Statistics for User Research. 2nd edn. Cambridge, MA: Morgan Kaufmann.

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