In Excel or Google Sheets, click-to-open rate for a whole period is SUM(AJ2:AJ7) / SUM(AI2:AI7), where each SUM covers one column of monthly figures. On the sample data it returns 12.52%.
Click-to-open rate = Unique clicks ÷ Unique opens × 100
What you need
Click-to-open rate (CTOR) is the percentage of people who opened an email and then clicked a link in it: unique clicks divided by unique opens, times 100. You need these columns, here from the sample file monthly.csv:
- Emails opened: column AI (email_opened)
- Emails clicked: column AJ (email_clicked)
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(AJ2:AJ7) / SUM(AI2:AI7) 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 =AJ2 / AI2 and drag the fill handle down to row 7.
- Format the results as a percentage (Home → %, or Format → Number → Percent in Sheets). The formula returns a fraction such as 0.45, which the format shows as 45%.
- If a month can have zero in the denominator, wrap the formula so it shows a blank instead of #DIV/0!: =IFERROR(AJ2 / AI2,"").
The formulas
=SUM(AJ2:AJ7) / SUM(AI2:AI7)=AJ2 / AI2What you should get
Run against the sample data, the code above returns these values:
| Month | email_opened | email_clicked | ctor |
|---|---|---|---|
| 2026-01 | 7,920 | 960 | 12.12% |
| 2026-02 | 8,160 | 1,020 | 12.50% |
| 2026-03 | 8,940 | 1,140 | 12.75% |
| 2026-04 | 8,800 | 1,050 | 11.93% |
| 2026-05 | 9,540 | 1,220 | 12.79% |
| 2026-06 | 9,770 | 1,260 | 12.90% |
| Whole period | 53,130 | 6,650 | 12.52% |
6,650 ÷ 53,130 × 100 = 12.52%
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 click-to-open rate misleads
- Use unique counts on both sides.
- Low opens can make CTOR jumpy; check the counts behind it.
- It does not measure revenue; follow clicks through to orders where you can.
The full explanation, with a calculator, is on the Click-to-open rate (CTOR) page.
Same metric, other tools
Related metrics in Excel and Google Sheets
Learn more about Excel
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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