How we test, and every result
We take real spreadsheets other people made, convert them, open them in the real other product, and compare every formula's result with the value the original calculated. A cell matches when the two results are equal. The numbers below say how many matched, out of how many.
The results
| Collection | Workbooks | Formula cells | Cells that match | Every cell matches |
|---|---|---|---|---|
| 27 real workbooks, imported by handConverted, then opened with Google Sheets' own File → Import, the way you will. | 27 | 126,268 | 99.99% | not recorded |
| The same files imported into Google Sheets without SheetSure: 70.0% of the cells match. | ||||
| EnronSpreadsheets used at a real company in 2000–01: a random sample of 1,000, of which 925 are counted (why: see the fine print). | 925 | 1,808,309 | 99.87% | 892 of 925 |
| Leaving out 25 workbooks whose saved values are out of date (see below): 99.990%. Converted to Google Sheets and back to Excel, 142 of 150 random workbooks still match in every cell. | ||||
| SpreadsheetBench912 real questions from an Excel help forum: the asker's workbook and the expert's answer. | 887 | 188,095 | 99.6% | 822 of 887 |
| Askers' workbooks: 81,054 cells, 293 of 324 match in every cell. Experts' answers: 107,041 cells, 529 of 563. One workbook downloaded from Google Sheets is left out and checked on its own. All 400 askers' workbooks in the first test converted without an error. | ||||
| Financial modelsAswath Damodaran's (NYU Stern) valuation models and open-source 3-statement, LBO and comps templates, with circular references. | 7 | 4,549 | 98.5% | 6 of 7 |
| Converted to Google Sheets and back to Excel, all 7 match in every cell. Imported by hand: the templates match on 309 of 309 cells, 4 of the Damodaran models on 4,173 of 4,240 (98.42%). | ||||
| Older financial modelsDamodaran's models saved by Excel 97–2003 (.xls). | 66 | 15,124 | 97.2% | 53 of 66 |
| Google Sheets → ExcelGoogle Sheets downloaded as .xlsx, converted, then recalculated in real Excel. | 28 | 90,406 | 99.18% | not recorded |
How the bigger collections were tested. Opening thousands of files by hand isn't practical, so for the large collections our test program puts each converted workbook into Google Sheets automatically, instead of using File → Import. To make sure that doesn't change anything, we ran the 27 workbooks above both ways: every cell came out the same.
Can I trust the Report tab in my file?
Yes, on everything we've checked. On 130,817 cells in 34 workbooks, the Report tab inside the converted file said exactly what our own test program said. The optional “Check the result” upload agreed on every formula too: 97,010 of 97,010 cells going to Google Sheets (33 workbooks), and 94,165 of 94,165 going to Excel (32 workbooks, saved by real Excel).
What still differs, and why
- 27 workbooks imported by hand. The 0.01% that differ are the same cells that differ in our automated test runs.
- Enron. Most of what's left is in 25 workbooks saved with automatic calculation turned off (or an old Lotus 1-2-3 setting), so the values stored in them are out of date and even Excel wouldn't reproduce them today.
- Financial models. The differing cells are in one of the seven models. After converting to Google Sheets and back to Excel, all seven match in every cell.
- Google Sheets → Excel. One test workbook's download from Google didn't open in Excel at all.
- Circular references: each product stops its repeated calculation at a slightly different point, so results can differ in the last digits (802.6496906 against 802.6496913). The Report tab in your file allows for this: it compares such workbooks to about 6 significant digits.
Each measured difference, with the rewrite for it, is in the differences catalog.
Fine print
- What “match” means
- The formula's result in the other product equals the value the original product calculated and saved in the file, in the real products. Numbers match when they agree to about 9 significant digits. A result within 0.00000001 of zero counts as zero, and XIRR is compared to 7 digits, because Excel's own XIRR is only that precise.
- Circular references
- The Report tab in your file compares a workbook that uses circular references to about 6 significant digits, because each product stops its repeated calculation at a slightly different point.
- Not compared
- Cells that change on every calculation (NOW, TODAY, RAND and the cells that read them): there's no fixed value to compare.
- Where the workbooks come from
- The Enron spreadsheet corpus, SpreadsheetBench, Aswath Damodaran's spreadsheets and open-source financial-model templates.
- Why 925 of the 1,000 Enron workbooks
- All 1,000 were converted and checked; 925 had at least one cell that could be compared. In 73, every formula either changes on every calculation (like NOW or TODAY) or has no Google Sheets equivalent and keeps Excel's value, so there was nothing to compare. The other 2 were too big for Google Sheets, which allows 10 million cells per spreadsheet.
- Why 66 of the 67 older models
- The 67th is a read-me sheet with no formulas, so there was nothing to compare.