Fred Reicheld, ideator of the Net Promoter Score (NPS) score, acknowledged that different scoring scales could be used and even provided a case study using a 5-point scale. Additionally, our expert research suggests that whether we use a 5-point or 11-point question scale, we measure the same underlying feeling/intention.
Why the 0-10 NPS scale isn't necessarily the best scale
Traditionally, the NPS customer-focused response scale ranges from 0 to 10 (11-point scale). These types of score 'out of 10' methods were once common for telephone interviews. Researchers start the scale at 0 because sometimes people would mistakenly use 1 as a good score. Which means that when a scale ranges from 0 to 10, it requires more respondent effort and time to understand and complete. Furthermore, scales from 0-11 are much less user-friendly for digital surveys, even more so on mobile devices. The majority of evidence suggests that fully labeled response scales are the most reliable response method. Without fully-labeled response scales, this can cause confusion and a decrease in respondent participation due to not understanding the scale (e.g., what's the difference between a 6 and a 7), and more time to complete.
The 0-10 eNPS scale or any other single question is never as reliable an outcome measure as a multi-question index
It's common statistical knowledge and recommendation that when it comes to self-report scale metrics for a critical outcome, we are far better off using a multi-question approach (e.g., we combine 3-4 questions into a single index for Employee Engagement). Customer and market research studies have shown that using multiple questions is more reliable and accurate than using a singular NPS-type question or metric.
Why the 0-4 NPS scale isn't necessarily the best scale
While the 4-point scale forces respondents to make a choice — removing a neutral option — it potentially has several drawbacks:
Lack of a midpoint skews responses: Without a neutral option, respondents may feel pressured to choose a side, even if they don’t have a strong opinion. This can lead to exaggerated or inaccurate results.
Reduces response validity: Research suggests that when respondents are forced into a polarized choice, their answers may reflect momentary feelings rather than true sentiment, decreasing the reliability of the data.
Limits differentiation: A 4-point scale offers less granularity, making it harder to distinguish between moderately positive and highly positive respondents. This limits the ability to accurately segment and analyze feedback.
For these reasons, a 4-point scale can introduce more noise into survey results rather than improving clarity.
How we calculate our eNPS score
Most customer-oriented NPS research uses an 11-point (0-10) scale (more on this below). However, we use 5-point Likert response formats in our surveys for better usability. Our own research (also others, e.g. here) has demonstrated the validity of a 5-point-based eNPS calculated as follows:
eNPS = Promoters - Detractors
Promoters = percentage of strongly agrees (5's)
Passives = percentage of agrees (4's)
Detractors = percentage of strongly disagrees, disagrees, and neutrals (1-3's)