How to Calculate Net Promoter Score (NPS)
Net Promoter Score (NPS) is one of the most common indicators of customer loyalty, yet many teams still report it without documenting the underlying response counts. A defensible NPS calculation starts with clear survey definitions, then translates response counts into promoter and detractor shares so leaders can interpret changes across periods, segments, and product lines.
This walkthrough explains the formal definition, the variable units, and the exact steps needed to calculate NPS. It also shows how to validate the result, interpret limits, and connect NPS to retention metrics such as the gross revenue retention framework and supporting financial models like the customer acquisition cost calculator.
Definition and scale of measurement
NPS measures the balance between customers who are likely to recommend your product and those who are unlikely to do so. Survey respondents score a single question on a 0 to 10 scale. Scores of 9 or 10 are promoters, 7 or 8 are passives, and 0 through 6 are detractors. The metric is expressed in percentage points, ranging from -100 to 100.
Because NPS is based on proportions, it is agnostic to survey volume, but the reliability of the result still depends on sample size, response bias, and consistent collection windows. Keep the survey instrument stable so year-over-year comparisons reflect customer sentiment rather than methodological drift.
Variables, symbols, and units
Every input is a count of responses within the reporting window. Use whole numbers or aggregated counts from your survey platform and record the total response volume alongside the final score.
- P – Promoter responses (scores 9-10), unit: responses.
- Pa – Passive responses (scores 7-8), unit: responses.
- D – Detractor responses (scores 0-6), unit: responses.
- N – Total responses, N = P + Pa + D, unit: responses.
- NPS – Net Promoter Score, unit: percentage points.
Core formula
NPS is the share of promoters minus the share of detractors. Passives influence the denominator but do not enter the numerator.
Promoter share = P ÷ N
Detractor share = D ÷ N
NPS = (Promoter share − Detractor share) × 100
Because the formula uses proportions, a higher total response count reduces volatility. Record the response volume alongside the NPS headline, especially for segment-level analysis.
Step-by-step calculation workflow
Step 1: Define the survey window and segment
Fix the survey period and the customer population. A quarterly NPS should include all responses collected in that quarter and apply consistent eligibility rules. When segmenting, document the segment definition so comparisons with growth and retention metrics remain meaningful.
Step 2: Categorize responses into promoters, passives, and detractors
Export the 0 to 10 scores, count how many fall into each category, and record the counts as P, Pa, and D. Keep raw totals for auditability and reruns.
Step 3: Compute the total responses
Sum the three response counts to produce N. If N is zero, the survey did not collect valid responses and NPS cannot be reported.
Step 4: Calculate NPS and round consistently
Apply the formula and round to two decimal places for internal tracking or to whole numbers for public reporting. Use a consistent rounding rule to prevent artificial quarter-over-quarter swings.
Validation and reconciliation checks
Confirm that P + Pa + D equals the total survey responses recorded by your system. Reconcile any discrepancies with duplicate records, disqualified responses, or excluded segments. Then compare the calculated promoter and detractor shares against trend dashboards so you can explain movements in retention metrics such as the net dollar retention calculator.
For small samples, compute confidence intervals or flag the result as directional. Large swings driven by fewer than 100 responses should be validated with qualitative feedback before they reach executive scorecards.
Interpretation limits and reporting guidance
NPS is a sentiment proxy, not a causal predictor. It does not measure revenue, adoption depth, or support workload on its own. Use it alongside churn, renewal, and customer success health scoring to avoid overreacting to a single survey wave.
If you survey multiple channels, keep NPS results separate unless the customer mix is comparable. When publishing externally, include the survey period, geography, and customer segment to prevent misinterpretation.
For executive dashboards, pair the headline NPS with a short list of top detractor themes and a note on sample size. This combination helps leaders understand whether a five-point shift signals a broad sentiment change or a concentrated issue in a specific workflow.
Worked example for a quarterly customer survey
Suppose your Q1 survey yields 550 promoters, 300 passives, and 150 detractors. Total responses are 1,000. Promoter share is 55%, detractor share is 15%, and NPS is (55% − 15%) × 100 = 40.00 points. The score can be reported as 40, but internal dashboards should preserve the decimal precision for benchmarking.
Embed: Net Promoter Score calculator
Use the embedded calculator to automate the arithmetic, document your response counts, and compare the output with your target benchmark. Keep the output alongside the response volume to maintain an audit trail.