Key takeaway
Reading a stored formula value is not evidence that its inputs and external links were recalculated.
Keep formula, stored value and displayed value apart
A workbook export can contain three different things: formula text, a saved result and a formatted display. A recipient may see a plausible total even though the formula has not been recalculated against the latest inputs. Ask which representation was read and which one the proposed analysis needs. Treating these representations as interchangeable can hide a stale result inside a clean-looking CSV.
The openpyxl tutorial says its data_only setting chooses formula text or a value stored when Excel last read the sheet. Its formula documentation also says the library does not evaluate formulas. Microsoft documents manual calculation settings and cautions about updating a link from a source workbook that has not fully recalculated. None of those settings proves the external source itself is correct or authorized to share.
A changed quantity with an unchanged saved total
In this hypothetical workbook, cell B2 contains quantity 6 and C2 contains unit price 10. Cell D2 contains the formula B2 × C2, but its saved value is 50 from an earlier quantity 5. These invented figures are unitless calculation inputs, not an offer or per-record price. An extractor reading only stored values can output 50 while a reviewer calculating the stated formula expects 60.
The useful decision is to hold the derived field until the difference is explained. Do not silently overwrite 50 with 60 and describe that as the original workbook result. Retain both the saved value and the independently derived test value with their origins. If the formula refers to an unavailable external workbook, the recipient cannot establish a fresh result by inspecting the local formula alone.
| Representation | Invented content | What it establishes | Receiving decision |
|---|---|---|---|
| Formula text | B2 × C2 | Intended local calculation | Retain with sheet and cell identity |
| Current local inputs | 6 and 10 | Available operands in this fixture | Expected test result 60 |
| Saved value | 50 | Stored result observed in file | Mark unresolved cache mismatch |
| Formatted display | 50.00 | Rendering of saved value | No extra calculation evidence |
Recalculate only within a controlled review
Before any recomputation, preserve the original file and record its hash, workbook version, calculation mode and unresolved dependencies. Ask the owner which application and calculation behavior produced the export. A new calculation should produce a separate reviewed output with a timestamp and explanation, so the receiving team can distinguish correction from original evidence.
Do not refresh external connections, macros or remote links merely to make the numbers agree. Those operations need an authorized technical environment and a review of what they access. Compare representative totals, conditional formulas and error cells against the owner’s approved calculation process. A workbook that opens without warning can still depend on missing inputs or a stale source system.
Publish a field map with an explicit unresolved state
For derived columns, retain source sheet/cell, formula or approved transformation, cached value, recomputed test value, calculation application/version, dependency status and discrepancy decision. Separate a missing cached value from numeric zero and from an actual formula error. Record whether rounding applies before or after aggregation; the display format is not the calculation specification.
For the toy example, the release decision remains a hold on D2 until the owner explains the saved 50 and authorizes a corrected result if appropriate. The worksheet’s raw inputs might have a different acceptance decision, provided their meaning and authority are established. Use the inventory builder to record the dependent field and the readiness planner to assign reconciliation. This check does not settle ownership, privacy, licensing permission or the value of a workbook archive.