How Excel silently destroys your GTINs (and how to get them back)

Updated July 2026

Spreadsheet conversion accounts for many of the invalid GTINs found in catalog audits. The changes often happen when a CSV is opened, before anyone edits a cell.

The two failure modes

1. Leading zeros stripped

Excel treats a GTIN as a number, and numbers do not have leading zeros. 036000291452 silently becomes 36000291452. Eleven digits is not a valid GTIN length, even though the final digit still satisfies the check-digit calculation.

2. Scientific notation

Any number longer than 11 digits may be displayed and exported as 8.85911E+11. Unlike the leading-zero problem, this is unrecoverable from the file alone. The original digits are gone.

Prevention

• Format the GTIN column as Text before you paste or import anything into it.
• When opening a CSV, use Data → From Text/CSV and set the GTIN column type to Text in the import dialog. Double-clicking the file skips this step and the damage is done before you see the sheet.
• Export as CSV with the column still formatted as Text. Open the raw file in a text editor and confirm that every digit is still present.
• Google Sheets has the same behavior. Format → Number → Plain text, before pasting.

Recovery

For stripped leading zeros, zero-pad back to a valid length (8, 12, 13, or 14 digits) and verify the check digit. A successful validation is strong evidence that the identifier was recovered. For scientific-notation damage, go back to the source system; the spreadsheet no longer contains the answer.