Excel Migration Validation Checklist: How to Verify Nothing Was Lost

January 26, 2026 · 5 min read

Converting an Excel file from .xls to .xlsx or .xlsm is a five-minute operation. Verifying that nothing was lost is where most migrations cut corners — and where problems get discovered by users in production. Use this checklist before signing off on any migration.

Pre-Validation Setup

Open both the original .xls and the converted .xlsx/.xlsm side by side in separate Excel windows. You need both open to compare outputs.

Make sure you're running the converted file on the target platform — 64-bit Excel on Windows 11 — not the development machine where it may have been converted.

Data Integrity Checks

☐ Row count on every sheet matches between original and converted
☐ Column count on every sheet matches
☐ Cell A1 values on each sheet match
☐ Last row of data on each sheet matches
☐ Total/summary formulas on each sheet produce the same results
☐ Any named ranges are present and point to correct ranges

Formula Checks

☐ Sample 10 formula cells across different sheets — values match original
☐ Date values display correctly (check for 1462-day offset if using 1904 date system)
☐ Array formulas (shown with {}) are present and calculate correctly
☐ No unexpected #REF!, #NAME?, or #VALUE! errors that weren't in the original
☐ External link formulas updated to new source file paths

Formatting and Visual Checks

☐ Cell formatting (number formats, date formats, currency) matches original
☐ Conditional formatting rules are present and firing correctly
☐ Column widths and row heights are consistent
☐ Merged cells are preserved
☐ Print areas and page breaks are set correctly
☐ Header/footer content matches original

Chart and Pivot Table Checks

☐ All charts are present and render correctly
☐ Chart data series reference correct source data
☐ Chart titles, axis labels, and legends match original
☐ All pivot tables are present
☐ Pivot tables refresh correctly (Data > Refresh All)
☐ Pivot table formatting and groupings are preserved

VBA and Macro Checks (.xlsm files)

☐ VBA editor opens without compile errors (Debug > Compile Project)
☐ All modules, class modules, and form code present
☐ No MISSING entries in Tools > References
☐ Each macro runs without runtime errors
☐ Macro outputs match original (if calculable)
☐ Form controls respond to clicks and interactions
☐ ActiveX controls load and are interactive

External Links and Connections

☐ Data > Edit Links shows no "Error: Source not found" entries
☐ All linked data refreshes correctly
☐ Any ODBC connections still authenticate and return data
☐ SharePoint list connections work if applicable

End-User Sign-Off

Before deployment, have the file's primary user open it and perform their typical workflow. IT can verify technical correctness but can't always verify that a business calculation is producing the right result — only the user who works with it daily can confirm that.

Get a written sign-off (even a quick email "looks good to me") before replacing the original with the converted version in the production location.

LegacyLeaps generates a validation report automatically

Row counts, formula checks, reference validation — all documented per file. You still do the end-user sign-off, but the technical verification is handled.