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- Import the CSV through Excel’s text/CSV import route.
- Set identifier columns to Text before loading the data.
- Re-export and compare the codes with the untouched source.
Import instead of double-clicking
Keep an untouched copy of the CSV. In Excel, use Data → From Text/CSV and open the transformation view before loading. Set the SKU column’s data type to Text. Microsoft documents this import route; wording varies between Excel versions. Check for an earlier automatic type-conversion step if the preview has already changed the codes.
Separate identifiers from quantities
Product codes, barcodes, postal codes, and account references usually need text semantics. Pack quantities and prices usually need numeric semantics. Applying one type to the entire sheet can solve the identifier problem while making calculations awkward. Define each column deliberately.
| Input value | What to verify |
|---|---|
| 00123 | All five characters remain |
| 00000 | The code is not treated as blank |
| 12345678901234567 | Every digit matches the original |
| 1E10 | It remains the literal product code |
| 03-04 | It does not become a date |
Formatting is not recovery
A custom number format can display extra zeros, but display formatting does not prove the stored identifier is correct. Microsoft also documents Excel’s 15-significant-digit numeric precision limit. If an import has already changed a long identifier, return to the original source rather than padding or reconstructing it from the damaged workbook.
Test the next handoff
Save the reviewed data in the format your catalog or purchasing system expects. Then inspect the exported file with a plain-text viewer, or reimport it with the identifier column explicitly set to Text. Compare a sample containing the edge cases above. A workbook that looks correct can still produce the wrong external file.
Keep a repeatable import rule
Write down which columns are identifiers and keep a tiny sample file for future checks. Use the same process when a supplier adds a new field or changes its export. For recurring work, retain the transformation settings so the next file does not depend on someone remembering a formatting trick.
Sources
Updated October 30, 2026. Based on the linked documentation; the tools have not been benchmarked by NarrowTools. Editorial policy