In Excel or Google Sheets, net Promoter Score for a whole period is ((SUM(AL2:AL7) - SUM(AN2:AN7)) / (SUM(AL2:AL7) + SUM(AM2:AM7) + SUM(AN2:AN7)))*100, where each SUM covers one column of monthly figures. On the sample data it returns 43.02.
NPS = (Promoters − Detractors) ÷ All respondents × 100
What you need
Net Promoter Score (NPS) is the percentage of survey respondents who are promoters (score 9–10) minus the percentage who are detractors (0–6), on the question "how likely are you to recommend us?". You need these columns, here from the sample file monthly.csv:
- NPS promoters (9–10): column AL (nps_promoters)
- NPS passives (7–8): column AM (nps_passives)
- NPS detractors (0–6): column AN (nps_detractors)
Step by step
- Download monthly.csv below and open it: in Excel use File → Open; in Google Sheets use File → Import → Upload. The headers land in row 1 and the six months in rows 2 to 7.
- Click any empty cell and enter =((SUM(AL2:AL7) - SUM(AN2:AN7)) / (SUM(AL2:AL7) + SUM(AM2:AM7) + SUM(AN2:AN7)))*100 for the whole six months. It adds up each column first and then does the arithmetic once, which is the correct way to combine months.
- For each month, click AQ2, enter =((AL2 - AN2) / (AL2 + AM2 + AN2))*100 and drag the fill handle down to row 7.
- Format the results as a number with two decimals.
- If a month can have zero in the denominator, wrap the formula so it shows a blank instead of #DIV/0!: =IFERROR(((AL2 - AN2) / (AL2 + AM2 + AN2))*100,"").
The formulas
=((SUM(AL2:AL7) - SUM(AN2:AN7)) / (SUM(AL2:AL7) + SUM(AM2:AM7) + SUM(AN2:AN7)))*100=((AL2 - AN2) / (AL2 + AM2 + AN2))*100What you should get
Run against the sample data, the code above returns these values:
| Month | nps_promoters | nps_passives | nps_detractors | nps |
|---|---|---|---|---|
| 2026-01 | 142 | 61 | 37 | 43.75 |
| 2026-02 | 150 | 66 | 42 | 41.86 |
| 2026-03 | 161 | 70 | 39 | 45.19 |
| 2026-04 | 148 | 72 | 48 | 37.31 |
| 2026-05 | 170 | 75 | 41 | 45.10 |
| 2026-06 | 181 | 79 | 45 | 44.59 |
| Whole period | 952 | 423 | 252 | 43.02 |
(952 − 252) ÷ (952 + 423 + 252) × 100 = 43.02
Notes for Excel
- Google Sheets accepts the same formulas. If your spreadsheet locale uses a comma as the decimal separator, Sheets and Excel expect semicolons between function arguments instead of commas.
- Averaging the monthly results with AVERAGE() gives a different and usually wrong answer for the period, because every month counts the same however large it was.
- Excel tables (Insert → Table) let you write the same formula with column names instead of letters, which is easier to read and survives inserted columns.
Where net Promoter Score misleads
- Passives (7–8) count in the denominator even though they are not in the numerator.
- Small samples swing a lot; one more detractor among 40 replies moves NPS by several points.
- Who answers matters. Surveys sent right after delivery and surveys sent after a support ticket give different scores.
The full explanation, with a calculator, is on the Net Promoter Score (NPS) page.
Same metric, other tools
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About the data on this page
The figures come from a small made-up dataset, printed above in full so you can check every number by hand. Download it as monthly.csv. The results are computed from those rows when the page is built, and the Excel formulas, SQL and Python on these pages are run against the same rows before publishing, so the code and the answers agree.
To get these numbers from your own data without writing formulas, try AnalyzeIt: ask in plain words and it shows the working behind every figure.
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