Check Formulas After Combining Workbooks
Check formulas after combining workbooks by verifying the values they contributed, not by expecting the formula expressions to remain in the download. CombineSheets exports values only. A formula cell contributes its last saved result, also called its cached value. That result can be present and still be older than the latest changes to the source data.
The practical sequence is to refresh the original workbook in your spreadsheet app, recalculate it, save it, and then combine the saved file. Keep the original for live calculations and use the combined output as a table of values that you can compare against it.
Why combined workbooks keep saved values
Appending rows and matching columns can move values into new positions. Duplicate removal can also remove rows. A formula expression copied into that new arrangement might refer to different cells or depend on sheets that are absent from the result.
The output therefore contains saved values rather than relocated formula expressions. Separate sheets mode also exports values only. Choosing that mode or using a pass does not preserve formulas, external links, or formatting.
This matters even for a simple row calculation. Imagine your own report calculates Revenue from Units and a price field. The downloaded Revenue cell contains the saved answer from the source workbook. Changing Units in the output will not automatically update that answer because the original expression is no longer there.
That illustration describes a possible report structure, not the contents of the supplied samples. sales-january.xlsx and sales-february.csv are specified as small order datasets; do not assume they contain formula examples. Use a workbook you know contains formulas when testing this workflow.
Understand a missing cache and an old cache
A missing cached value means there is no saved formula result available for export. The tool stops and asks you to recalculate and save in your spreadsheet app. It does not silently replace the missing result with a blank.
An old cached value is different. There is a saved answer, but it may reflect earlier inputs. Its presence does not establish that the workbook has been recalculated since the most recent edit. A successful export cannot establish that either.
| Source condition | What to do |
|---|---|
| Formula has no saved value | Recalculate and save in the original app, then retry |
| Formula has a saved but possibly old value | Refresh the source and compare the recalculated result |
| Formula depends on another workbook | Check that dependency in the original app before saving |
| Output value looks reasonable | Still compare it with the refreshed source |
Treat recalculation as a preparation step, not as a repair to the merged file. Once an expression has been exported as a value, the combined file no longer contains the original calculation to refresh.
Recalculate and save before combining
Open each formula-driven source in the spreadsheet app that normally calculates it. Check that the inputs needed by the formulas are available. If the workbook depends on another file, verify that the linked source is the intended version.
Run the app's recalculation workflow, review important totals, and save the workbook. Use that saved version as the input to the merge. Saving an unrelated copy or selecting an older download can undo the benefit of this step.
Before closing the source, note a few values you will compare later. Useful choices include a line-item calculation, a subtotal that covers known records, and a final total. Include an empty cell and a zero if the distinction matters to your report.
Check the table structure too. The first non-empty row becomes the header, and names match without regard to case or surrounding spaces. Use the worksheet selection workflow to exclude summaries or helper sheets that should not be appended to detail records.
External links need attention in the source app
External links are not preserved in the output. A formula depending on another workbook can contribute its saved result, but the downloaded value will not remain connected to that workbook. Later changes to the external source will not flow into the combined table.
Check those dependencies while you still have the original open. Confirm that the expected external file or source was available when the calculation was refreshed. If you cannot establish that the saved answer is current, do not treat the exported answer as verified.
Recalculate and save after resolving a dependency. If the formula still has no saved value, the export stops again. Changing the output format to CSV or choosing a pass does not restore an absent cache or preserve the external link.
Spot-check totals after merging
Open the main merge tool, select the intended source sheets, and review the mapping report. Add the optional Source file column if you need to trace records back to a particular input. For multi-sheet workbooks, the tracking value includes the workbook and sheet names.
First reconcile the row figures: rows read, empty rows skipped, duplicates removed, and output rows. A total can change because the set of records changed, even when every exported value matches its source.
The monthly samples illustrate this distinction without requiring formulas. They contain 12 data rows across both inputs and one deliberate duplicate. With duplicate removal enabled, 11 data rows remain. Comparing a total over those 11 rows with an unchecked sum of all 12 input rows would use different record sets.
Then compare the saved formula results you noted earlier. Match records by their business identifiers, not only by row number, because appending and duplicate removal affect positions. Check that values landed under the correct output headers and that missing columns are represented by empty cells.
For an overall total, calculate over the same selected records in your spreadsheet app. Avoid including a source summary row alongside its detail rows unless that is intentional. The merge appends records; it does not decide whether two levels of reporting should be added together.
Keep a clear boundary between source and output
Use the downloaded file as a values table. If you need future calculations, add and review them in your own spreadsheet workflow, or return to the original workbook and generate a new checked export after changes.
The output also loses fonts, fills, borders, column widths, merged-cell layout, conditional formatting, validation, comments, images, charts, pivot objects, macros, and external links. These losses are separate from whether a saved formula value is correct.
Keep the original files, the reviewed output, and enough context to explain which sheets and duplicate settings produced it. For a practical column-order example, follow the monthly reports walkthrough. The final check is that the exported values represent the records and calculation state you actually intended to share.