# Convert XLS to XLSX

> Convert XLS to XLSX online for free in seconds. Files are processed in a secure, isolated sandbox and deleted automatically. No sign-up, no watermarks.

URL: https://www.converterrr.com/xls-to-xlsx

- Runs in an isolated cloud sandbox with LibreOffice: files are deleted automatically, and the job uses cloud credits.
- Engines: LibreOffice (cloud).
- API: available. `POST /api/v1/jobs` with `"output_format": "xlsx"` (paid plans).
- More: [Spreadsheet converter](https://www.converterrr.com/spreadsheet-converter), [XLS converter](https://www.converterrr.com/xls-converter).

## How to convert XLS to XLSX

1. **Add your XLS files.** Drag and drop XLS files onto the converter, paste them, or click to browse. You can add several at once.
2. **Choose XLSX.** XLSX is already selected. Open Options if you want to change quality, size or metadata.
3. **Convert.** Click Convert. Files are processed in a secure cloud sandbox and are usually ready in seconds.
4. **Download your XLSX.** Download each XLSX file, or everything at once as a ZIP.

## Good to know

- XLS files are typically used for older Excel workbooks, while XLSX is best for spreadsheets in Excel, Google Sheets and Numbers.
- This conversion runs on LibreOffice in an isolated cloud sandbox. Files are encrypted in transit and deleted automatically.

## XLS vs XLSX

|  | XLS | XLSX |
| --- | --- | --- |
| Full name | Microsoft Excel 97–2003 | Microsoft Excel Workbook |
| Type | Spreadsheet | Spreadsheet |
| Extensions | .xls | .xlsx |
| MIME type | application/vnd.ms-excel | application/vnd.openxmlformats-officedocument.spreadsheetml.sheet |
| Best for | older Excel workbooks | spreadsheets in Excel, Google Sheets and Numbers |
| Properties | legacy format, proprietary | open standard |

**XLS:** XLS is the legacy binary Excel format used before 2007.

**XLSX:** XLSX is the modern Excel workbook format with formulas, multiple sheets, charts and formatting.

The other way around: [convert XLSX to XLS](https://www.converterrr.com/xlsx-to-xls).

## Related conversions

- [XLSX to XLS](https://www.converterrr.com/xlsx-to-xls) (cloud)
- [XLS to PDF](https://www.converterrr.com/xls-to-pdf) (cloud)
- [CSV to XLSX](https://www.converterrr.com/csv-to-xlsx) (cloud)
- [XLS to CSV](https://www.converterrr.com/xls-to-csv) (cloud)
- [ODS to XLSX](https://www.converterrr.com/ods-to-xlsx) (cloud)
- [XLS to HTML](https://www.converterrr.com/xls-to-html) (cloud)
- [Numbers to XLSX](https://www.converterrr.com/numbers-to-xlsx) (cloud)
- [XLS to ODS](https://www.converterrr.com/xls-to-ods) (cloud)
- [TSV to XLSX](https://www.converterrr.com/tsv-to-xlsx) (cloud)
- [XLS to TSV](https://www.converterrr.com/xls-to-tsv) (cloud)

## Convert XLS to other formats

[XLS to PDF](https://www.converterrr.com/xls-to-pdf), [XLS to CSV](https://www.converterrr.com/xls-to-csv), [XLS to HTML](https://www.converterrr.com/xls-to-html), [XLS to ODS](https://www.converterrr.com/xls-to-ods), [XLS to TSV](https://www.converterrr.com/xls-to-tsv)

## Convert other formats to XLSX

[CSV to XLSX](https://www.converterrr.com/csv-to-xlsx), [ODS to XLSX](https://www.converterrr.com/ods-to-xlsx), [Numbers to XLSX](https://www.converterrr.com/numbers-to-xlsx), [TSV to XLSX](https://www.converterrr.com/tsv-to-xlsx)

## XLS to XLSX: frequently asked questions

### How do I convert XLS to XLSX?

Drop your XLS file onto the converter above, make sure XLSX is selected, and click Convert. When it's done, download the XLSX file — it usually takes a few seconds.

### Is it safe to convert XLS to XLSX here?

Yes. Your file is sent over an encrypted connection to an isolated sandbox that's created for your job only, then both the original and the result are deleted automatically.

### Is the XLS to XLSX converter free?

Yes. Cloud conversions like this one use credits, and you get free credits every day (3 without an account, 10 with a free account).

### Will converting XLS to XLSX reduce quality?

No — XLSX preserves the content of your XLS file as faithfully as the format allows.

### Can I convert multiple XLS files at once?

Yes. Add up to 5 files at a time without an account, 10 with a free account and up to 500 on paid plans, then download them individually or as a single ZIP.

### Can I convert XLSX back to XLS?

Yes — use our XLSX to XLS converter. Note that converting back and forth between formats can't recover detail lost to lossy compression.