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Data & Spreadsheets

XLS to XLSX

Old exports from banks and legacy systems come as XLS. Convert them to XLSX for modern Excel, Google Sheets and web apps that refuse the old format.

By Miikka · CalcBrew · Updated

Runs in your browser — files never leave your device.

Drop Excel 97–2003 (XLS) files here

or click to browse · paste from clipboard · up to 100 MB each

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Why convert Excel 97–2003 (XLS) to Excel (XLSX)

XLS is limited to 65,536 rows and 256 columns and is increasingly blocked by email filters because it can contain macros. XLSX is XML-based, safer and supported everywhere.

The binary format is parsed in your browser and rewritten as XLSX with values, formulas, formatting and sheet structure preserved.

How to convert Excel 97–2003 (XLS) to Excel (XLSX)

  1. Drop Excel 97–2003 (XLS) file onto the box above, click it to browse, or paste from the clipboard.
  2. Check the file list; remove anything you added by mistake.
  3. Press Convert. The work happens on your device, so speed depends on your computer or phone.
  4. Download the Excel (XLSX) — individually or all at once.

About the formats

Excel 97–2003 (XLS) · Legacy Microsoft Excel workbook · .xls

The binary Excel format used until 2007, limited to 65,536 rows and increasingly refused by web apps.

  • XLS supports 65,536 rows and 256 columns per sheet — larger data is silently cut off.
  • Many banks and legacy systems still export XLS.
  • Excel opens XLS in Compatibility Mode and recommends saving as XLSX.

Excel (XLSX) · Microsoft Excel workbook · .xlsx

The current Excel format: multiple sheets, formulas, formatting, charts and pivot tables in one file.

  • XLSX stores both the formula and its last computed value, so a converted CSV contains the values.
  • Maximum 1,048,576 rows and 16,384 columns per sheet.
  • XLSM is the same format with macros enabled.

Related conversions

Excel to CSVPopularOn-deviceExcel sheets to CSV with chosen delimiter and encoding.CSV to ExcelPopularOn-deviceCSV into a proper Excel workbook, delimiter auto-detected.Excel to JSONOn-deviceExcel sheets to JSON arrays with typed values.Excel to ODSOn-deviceExcel workbooks to open-standard ODS.CSV to JSONOn-deviceCSV rows into a JSON array of objects.JSON to CSVOn-deviceJSON arrays flattened into CSV columns.

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Cite this calculator
APACalcBrew. (2026). XLS to XLSX. https://calcbrew.com/xls-to-xlsx
MLA“XLS to XLSX.” CalcBrew, 2026, calcbrew.com/xls-to-xlsx.

Link to https://calcbrew.com/xls-to-xlsx. Results are estimates; cite the underlying formula or data source for academic work.