THE FILE FIELD GUIDE

.xls

Excel Workbook (legacy)

Spreadsheets

A legacy Excel binary workbook. Business files may contain macros and external links as well as formulas; identify required behavior before migration.

What it is used for: Migrating legacy Excel workbooks
What the file contains: Binary data

All sections, questions and sources

Content reviewed：2026-10-11 · Editor：Kai

First: choose for your purpose

XLS is a legacy workbook that may contain macros. Choose XLSX or macro-capable XLSM according to content. Preserve a copy and check old row/column limits and add-in dependencies.

Opening steps

Choose your environment or purpose to see its steps.

Windows: inspect Compatibility Mode

Inspect features before choosing a new format.

Open an XLS copy in Excel and review Compatibility Mode/macro notices.
Inspect sheets, formulas, links, buttons and old add-ins; do not enable code solely for viewing.
Save a separate XLSX or appropriate XLSM, read warnings and compare with the legacy copy.

macOS / Linux: check interoperability

Excel for Mac/Calc can differ in VBA and other behavior.

Open a copy in Excel for Mac or LibreOffice Calc.
Compare totals, dates and charts and ask about Windows-only or macro dependencies.
Choose the saved format explicitly and recheck important calculations in the source environment.

Mobile / web: conversion and reading

Browser use can convert the workbook.

Open a copy in a supporting Excel app/web environment.
Review conversion/feature notices and use the required desktop environment for macro-dependent work.
Check the resulting format and separate editable sources from PDF delivery.

Menu labels and support vary by app, OS and version. Preserve the original before making changes.

Troubleshooting by symptom

Legacy format limits can affect rows/columns and features. Compare a copy saved in a newer format.
Missing links require the source data. Displayed values alone do not prove calculations are reproducible.
New rows cannot be saved: inspect legacy limits/compatibility warnings and check for omissions before migration.
Buttons fail after migration: XLSX may have removed macros; return to the original for an appropriate export.
Repair requested: retrieve a complete original, repair a copy and compare formulas/sheets afterward.

XLS → XLSX (check macros first)

Save a copy as XLSX if no macros are needed; otherwise verify an appropriate macro-enabled format with the author.
Compare totals, charts and validation rules against the original.
Compare sheets, formulas, macro presence and totals before/after conversion.

XLSX cannot store VBA macros. Ignoring conversion warnings can remove business logic.

Migration checklist

XLSX is a normal workbook and XLSM is macro-capable; changing format does not guarantee compatibility of legacy macros/add-ins.

Compare sheets, key formulas, charts and print output and ask whether macros are required before selecting a format.

Source for these steps：Microsoft · File formats that are supported in Excel

Legacy dependencies

Locate referenced workbooks/data; visible values can exist without reproducible recalculation.

For managed legacy-only workflows, request verified-value/PDF copies rather than routinely bypassing security restrictions.

Related-format differences

Related-format differences
Format / choice	Purpose and preserved information
XLS	Legacy binary workbook with possible macros/features.
XLSX	Modern normal workbook without macro storage.
XLSM / PDF	XLSM stores macros; PDF distributes viewing/print output.

Handling and security

Do not automatically enable legacy macros/links. Verify the source and keep a backup.

Questions and answers

Does every XLS contain macros?

Not every file, but the format can contain them; inspect rather than infer.

Do macros survive XLSX saving?

VBA cannot be stored in XLSX. Use a suitable macro-enabled format if required.

What if Calc totals differ?

Check function compatibility, links and dates against the original Excel results.

Does XLSM migration guarantee macro execution?

No; old add-ins, APIs, operating systems and policy can matter.

Why did web editing produce XLSX?

Web handling may convert the legacy format; retain the original XLS.

Format facts: name, steward and MIME type

Formal name: Excel 97–2003 Binary Workbook
Steward / specification: Microsoft
MIME type: application/vnd.ms-excel

Primary and official sources

Official documentationOffice File Formats — Technical Documents
Lists technical specifications for DOC, XLS and PPT structures.
Microsoft · Link checked：2026-10-04
Software documentationOffice file format reference
Lists Office formats and the binary/XML distinction.
Microsoft · Link checked：2026-10-04
Software documentationUsing Microsoft Office and LibreOffice
Documents opening Office files with Writer, Calc and Impress.
The Document Foundation · Link checked：2026-10-04
Software documentationDifferences between using a workbook in the browser and in Excel
Browser conversion and macro-execution limitations.
Microsoft · Link checked：2026-10-11
Software documentationOpen a document after a file corruption error
Open and Repair for Office files and its recovery limits.
Microsoft · Link checked：2026-10-11
Software documentationFile formats that are supported in Excel
Differences in XLS, XLSX, XLSM and CSV storage.
Microsoft · Link checked：2026-10-11