Conversion path

XLS to XLSX API

Convert XLS files to XLSX format for compatibility, editing, sharing, and workflow flexibility.

XLS XLSX Spreadsheet to spreadsheet

Overview

Why convert XLS to XLSX?

XLS to XLSX conversion helps standardise structured data across tools, imports, reporting workflows, and spreadsheet ecosystems.

Converterer handles these conversions through API-driven and automation-first workflows rather than one-off manual file handling.

Common use cases

move data into the spreadsheet format your customer or stakeholder expects
improve compatibility between Excel, open formats, and data workflows
support imports, exports, and operational reporting

Quick example

Convert XLS to XLSX in one request.

xls-to-xlsx.sh bash

# Submit a XLS to XLSX conversion, get an ID back instantly.
curl -u "$CONVERTERER_API_KEY:" \
  https://api.converterer.com/convert \
  -F input=@source.xls \
  -F output_format=xlsx

# → {"id":"9f1a8e7c-1b9b-4f0a-9d2c-1a2b3c4d5e6f", "status":"queued"}
# The XLSX result lands at <your-destination>/<id>.xlsx when done.
# Subscribe to a webhook to be notified the moment it's ready.

Implementation

Ship XLS to XLSX with code or workflows.

Use the API guide

If you need this conversion inside a product, backend job, or repeatable workflow, the API guide is the best place to start.

Best next step: open the API guide for code examples, or use the automation guides for no-code and ops workflows.

View API guide

Need implementation paths?

How it is used

How this conversion is usually used.

Prepare the source XLS spreadsheet or data file

Run the XLS to XLSX conversion

Send the XLSX output into reporting, finance, ops, or data workflows

Format context

Format considerations.

About XLS

XLS is commonly used for older spreadsheets, finance and ops files.

legacy Excel compatibility

About XLSX

XLSX is often chosen for analysis, reporting, spreadsheet sharing.

modern Excel compatibility

Related paths

Related conversions.

CSV to XLSX

Convert CSV data files to Excel spreadsheet format with proper formatting and organization.

Apple Numbers to XLSX

Convert Numbers files to XLSX format for compatibility, editing, sharing, and workflow flexibility.

ODS to XLSX

Convert ODS files to XLSX format for compatibility, editing, sharing, and workflow flexibility.

XLS to CSV

Convert XLS files to CSV format for compatibility, editing, sharing, and workflow flexibility.

XLS to JPG

Convert XLS files to JPG images for previews, exports, and visual workflows.

XLS to ODS

Convert XLS files to ODS format for compatibility, editing, sharing, and workflow flexibility.

FAQ

Questions people ask about XLS to XLSX.

Why would I convert XLS to XLSX?

XLS to XLSX conversion helps standardise structured data across tools, imports, reporting workflows, and spreadsheet ecosystems.

Can I automate XLS to XLSX conversion?

Yes. Use the API guides or workflow pages to handle XLS to XLSX conversion in product flows, internal automation, or repeatable backend jobs.

What should I consider before converting XLS to XLSX?

XLS and XLSX have different strengths around compatibility, quality, file size, editability, and downstream tooling. Pick the output format that best matches the workflow you are targeting.

Ready to test it?

Start converting files in minutes.

Get into the API docs, grab a code recipe in your language, or wire up a no-code workflow. The free tier is enough to test against your real files.