SUS vs NPS: Which Metric Should You Use?
Both the System Usability Scale (SUS) and Net Promoter Score (NPS) are popular metrics for measuring user experience, but they measure different things. This guide explains when to use each and how they can complement each other.
Quick Comparison
| Aspect | SUS | NPS |
|---|---|---|
| What it measures | Perceived usability | Loyalty & likelihood to recommend |
| Number of questions | 10 questions | 1-2 questions |
| Score range | 0-100 | -100 to +100 |
| Average/benchmark | 68 | Varies by industry (0-50 typical) |
| Best for | Product/interface evaluation | Brand/company perception |
| When to administer | After using a product | Anytime during customer journey |
| Created | 1986 (John Brooke) | 2003 (Fred Reichheld) |
What is SUS?
The System Usability Scale (SUS) is a 10-question standardized questionnaire developed by John Brooke in 1986. It measures perceived usability of a product, system, or interface on a scale from 0-100.
Strengths
- Scientifically validated over 35+ years
- Provides detailed usability insights
- Works for any product type
- Easy to compare across studies
Limitations
- Requires recent product interaction
- 10 questions may feel long
- Specific to usability (not satisfaction)
- Complex scoring formula
What is NPS?
Net Promoter Score (NPS) is a customer loyalty metric developed by Fred Reichheld in 2003. It asks one question: “How likely are you to recommend [company/product] to a friend or colleague?” on a 0-10 scale.
Strengths
- Quick and easy (1 question)
- High response rates
- Widely used and understood
- Predicts business growth
Limitations
- Doesn't explain why
- Influenced by factors beyond UX
- Cultural bias in responses
- Overused and fatiguing
When to Use Each Metric
Use SUS when you need to...
- Evaluate a specific product, feature, or prototype
- Compare usability before and after a redesign
- Get actionable insights about ease of use
- Benchmark against industry standards (average: 68)
- Conduct usability testing sessions
Use NPS when you need to...
- Measure overall brand or company perception
- Track customer loyalty over time
- Get a quick pulse check from many customers
- Segment customers (Promoters, Passives, Detractors)
- Predict business growth potential
Using SUS and NPS Together
SUS and NPS aren't mutually exclusive—they measure different aspects of user experience and can provide a more complete picture when used together.
Recommended Approach
Use SUS for product-specific feedback
After usability testing, feature launches, or redesigns to measure how usable the product is.
Use NPS for relationship tracking
Quarterly or after key moments in the customer journey to gauge overall loyalty and satisfaction.
Correlate the data
Low SUS scores often correlate with low NPS. If users find your product hard to use, they're less likely to recommend it.
Frequently Asked Questions
Is SUS better than NPS?
Neither is universally better—they measure different things. SUS measures usability (how easy a product is to use), while NPS measures loyalty (likelihood to recommend). Use SUS for product evaluation and NPS for customer relationship tracking.
Can I replace NPS with SUS?
Not directly. SUS requires users to have recently interacted with your product and specifically measures usability. NPS can be sent to any customer at any time and measures overall perception. They serve different purposes.
What's a good SUS score compared to NPS?
A SUS score above 68 is above average, with 80+ being good and 90+ excellent. NPS benchmarks vary by industry—a score above 0 is generally positive, above 50 is excellent. The scales aren't directly comparable.
How often should I run SUS surveys?
Run SUS after significant product changes, during usability testing, or at regular intervals (monthly/quarterly) if tracking usability over time. Unlike NPS, SUS should be administered shortly after product use.
Do I need both metrics for a small product?
For small products or early-stage startups, SUS alone may be sufficient since usability is often the primary concern. Add NPS later when you have more customers and want to track loyalty.
Ready to measure usability?
Start with a SUS survey to understand how usable your product is.