xlsx

Use openpyxl to write formula strings directly into cells, such as sheet['B10'] = '=SUM(B2:B9)', rather than hardcoding computed values. After saving, recalculate the file with LibreOffice so formula cells contain cached values that other tools can read.

Use openpyxl when you need formulas, formatting, or cell-level edits, and pandas (read_excel, to_excel) for bulk data movement in and out of sheets. For a quick read-only look at a sheet's contents, markitdown renders each sheet without cell coordinates.

openpyxl writes formulas as strings with no cached values, so data_only=True reads return None until the file is recalculated. Run a LibreOffice-based recalculation pass, which computes every formula and rewrites the file in place.

Post-2007 functions like TEXTJOIN, IFS, and MAXIFS need an _xlfn. prefix to evaluate, while XLOOKUP, XMATCH, SORT, FILTER, UNIQUE, and SEQUENCE cannot be evaluated at all in this environment. Prefer Excel-2007-era functions such as SUMIFS, INDEX, MATCH, IFERROR, and SUMPRODUCT.

Macros in .xlsm files are lost unless you pass keep_vba=True to load_workbook. External links to other workbooks lose their cached values on save, so recalculation would resolve them to #NAME?; copy those values from the original file first.

A workbook loaded with data_only=True contains only cached values and no formulas, so saving it permanently replaces every formula with a literal value. Always edit on a normally loaded workbook and use a separate data_only load only for reading values.