How do I convert CSV to XLS?

Add your CSV file to the upload area above, then press Convert. The XLS file downloads straight to your device. You do not need an account, and there is no watermark.

Are my files uploaded to a server?

No. This conversion runs entirely inside your browser using WebAssembly, so the file never leaves your device — you can even disconnect from the internet after the page loads and it will still work.

Does converting to XLS reduce quality?

Text, structure and images carry over faithfully. Exact page layout does not, because XLS lays content out differently from CSV. Check headings, tables and page breaks in the result.

How large a file can I convert?

Up to 100 MB per file for this conversion. Because the work happens in your browser, the practical limit is your device's memory — larger files work on a desktop with plenty of RAM and may fail on an older phone.

Can I convert several files at once?

Yes. Add as many as you like and press Convert All. Each file is processed independently, so one failure does not stop the rest, and you can download everything together as a ZIP.

Can I use this on my phone?

Yes. FileTools360 works in mobile browsers on iOS and Android, including choosing files straight from your camera roll. Very large videos may run out of memory on a phone — those are better converted on a laptop.

SpreadsheetLayout rebuiltRuns in your browser

CSV to XLS Converter

Turn CSV files into XLS in a couple of clicks. Flat tabular text — one table, no formatting. Excel's pre-2007 binary workbook. Content is preserved and the layout is rebuilt for the target format.

On your deviceNever uploadedGone when you close the tabHow this works

Drop your files here

CSV files (.csv) · up to 100 MB each

or paste files from your clipboard

Ready when you are

Drop a CSV file above and FileTools360 will turn it into XLS — right here on your device, without uploading anything.

⌘K to search converters

How to use it

1
Add your CSV files
Drag them onto the upload area, choose them from your device, or paste them from your clipboard. You can queue several at once.
2
Adjust the settings if you want to
The defaults suit most people. Open Advanced to control delimiter and header handling.
3
Convert and download
Press Convert. Everything happens on your own device — nothing is uploaded. Download files one by one, or grab them all as a ZIP.

CSV and XLS explained

CSV is plain text where each line is a row and commas separate the fields. There is no formatting, no formulas, and no second sheet — which is precisely why every system on earth can read it.

The pre-2007 Excel format is a binary structure limited to 65,536 rows and 256 columns — limits modern datasets routinely exceed.

Where CSV files come from: Database exports, analytics tools and data interchange between systems.
Where XLS is used: Spreadsheets from Excel 2003 or earlier, and some legacy export systems.

CSV vs XLS

The two formats solve different problems, which is why converting between them involves trade-offs rather than a straight upgrade.

CSV compared with XLS
Property	Source	Target
Compression	None	None
Introduced	—	1987
Browser support	Every spreadsheet, database and programming language.	Still opens in Excel and LibreOffice.

CSV is stronger at: Readable by every spreadsheet, database and programming language. Plain text, so it diffs and streams well. Tiny files.
XLS is stronger at: Still opens in Excel and LibreOffice.

Why convert CSV to XLS?

People make this switch when they run into the limits of CSV: the data needs formulas, formatting or multiple sheets. XLS is the better fit when a legacy system demands it specifically.

CSV limitations that prompt the switch: Exactly one table — no sheets, formatting or formulas. No type information, so leading zeros and long numbers get mangled. The 'comma' is not guaranteed; European exports often use semicolons.
What you give up: Hard row and column limits. Larger files than XLSX.

What is preserved when converting CSV to XLS?

Both formats store the content without discarding data, so this conversion preserves it exactly. The file size may change because the two formats compress differently, but the content itself is unaffected.

CSV has no notion of data types. A product code like 007 becomes 7 unless the importing tool is told otherwise — which is a property of CSV, not a bug in the converter.