Convert XLS to XLSX online in seconds — free, with no sign-up. XLSX is lossless and ideal for data, calculations and shared spreadsheets. Your files are encrypted and deleted automatically after 24 hours.
XLS
Microsoft Excel (legacy) — The older binary Excel format, superseded by XLSX.
XLSX
Microsoft Excel — Excel's format storing sheets, formulas and charts as XML.
How to convert XLS to XLSX
- 1Upload your XLS file
Click “Choose a file” or drag and drop your XLS file onto the page — no sign-up or email needed.
- 2Convert to XLSX
XLSX is already selected as the output. Open Options to fine-tune quality if you like, then click Convert.
- 3Download your XLSX file
Your XLSX file is ready in seconds — click Download to save it. Files are automatically deleted after 24 hours.
XLS vs XLSX
| XLS | XLSX | |
|---|---|---|
| Full name | Microsoft Excel (legacy) | Microsoft Excel |
| Type | Spreadsheet | Spreadsheet |
| Compression | Lossless | Lossless |
| Best for | legacy spreadsheets; converted to XLSX or CSV | data, calculations and shared spreadsheets |
Frequently asked questions
Does converting XLS to XLSX lose quality?
Converting XLS to XLSX preserves your text, images and most formatting. Very complex elements — macros, live formulas or unusual fonts — may not carry over perfectly, but the content stays intact.
What's the difference between XLS and XLSX?
Microsoft Excel (legacy) (XLS) is lossless and best for legacy spreadsheets; converted to XLSX or CSV. Microsoft Excel (XLSX) is lossless and best for data, calculations and shared spreadsheets. Convert XLS to XLSX when you need a spreadsheet for data.
Is the XLS to XLSX converter free?
Yes — converting XLS to XLSX is completely free. There's no watermark, no sign-up and no email required, and you can convert as many files as you like.
Are my XLS files private and secure?
Yes. Your uploads are encrypted in transit, processed privately, and automatically deleted within 24 hours. We never share, sell or look at your files.
Can I convert XLS to XLSX on iPhone, Android, Mac or Windows?
Yes. The converter runs entirely in your browser, so it works on any device — iPhone, iPad, Android, Mac, Windows or Linux — with nothing to download or install.
How long does it take to convert XLS to XLSX?
Most files convert in a few seconds. Larger files take a little longer, and your upload speed is usually the limiting factor. There's no queue and no waiting for an email.
What else can I convert XLS files to?
Besides XLSX, you can convert XLS to CSV, ODS, PDF and more — see the full list of XLS conversions below.
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Last updated July 2026