CSV to XLS Converter
Processing entirely on your device — large files may take a moment.
Opening legacy .xls exports in modern tools is easiest after converting them to XLSX or CSV. If your files are still in CSV format, this page is the shortcut: CSV (Comma-Separated Values) is the universal spreadsheet export format: one table of rows and columns stored as plain text, opened by Excel, Google Sheets and every data tool.
iLoveConverter processes everything locally on your computer, which makes it private and fast: no upload wait, no server storage, no limits. Add as many files as you like — batch conversion is built in.
How CSV compares to XLS
| CSV | XLS | |
|---|---|---|
| Structure | One flat table | Multiple sheets (BIFF8) |
| Types / schema | Untyped (all strings) | BIFF8 typed cells |
| Compatibility | Excel, Sheets, databases, code | Legacy Excel systems |
| Best for | Data exchange and bulk import | Reading historical workbooks |
How to convert CSV to XLS
- 1
Select your files
Drag & drop your CSV files onto the area above, or click to browse. You can add multiple files at once for batch conversion.
- 2
Convert instantly
Click "Convert to XLS". The conversion runs entirely inside your browser using WebAssembly — no upload, no queue, no waiting.
- 3
Download results
Download each converted XLS file individually, or grab everything at once as a ZIP archive.
About the CSV format
CSV (comma-separated values) is the lowest common denominator of tabular data: one table, rows as lines, columns separated by commas, everything plain text. Excel, Google Sheets, every database importer, every data-science library and every scripting language read it, which is why it has survived fifty years of format fashion.
Its weaknesses come from the same minimalism. There are no types (everything is a string until you decide otherwise), no formulas, one table per file, and dialect quirks are legendary: comma vs semicolon locales, quoting rules, and Excel's insistence on re-opening UTF-8 files without a BOM as mojibake. Clean, well-formed UTF-8 CSV with a BOM sidesteps nearly all of it.
+Strengths
- ✓Universal: Excel, Sheets, databases and code all read it
- ✓Human-readable and diff-friendly
- ✓Streams well — process giant files line by line
!Limitations
- −No types, no formulas, no multiple sheets
- −Dialect chaos: delimiters, quoting, encoding
- −Nested or hierarchical data does not fit
About the XLS format
XLS is the legacy Excel binary format (BIFF8, Excel 97–2003). It does everything its era supported — sheets, formulas, formatting, VBA macros — under hard limits: 65,536 rows and 256 columns per sheet. Millions of government, banking and manufacturing templates were built on it, which is why it still arrives in inboxes.
There is no reason to create new XLS files: XLSX handles everything better with no row ceiling. The realistic use case is reading — opening or converting historical files, or feeding systems whose import filters predate 2007.
+Strengths
- ✓The only format ancient Excel-era systems accept
- ✓Full BIFF8 feature set: formulas, macros, formatting
!Limitations
- −65,536-row and 256-column ceiling per sheet
- −Obsolete binary spec, awkward for modern tools
- −Macro-enabled files carry security risk
Why convert CSV to XLS?
Converting makes sense where the strengths of XLS meet what CSV cannot give you. The only format ancient Excel-era systems accept Meanwhile No types, no formulas, no multiple sheets One pass through the converter above puts your file on the right side of that trade-off.
Frequently asked questions
Is this CSV to XLS converter really free?
Yes — completely free, with no sign-up, no watermark and no daily conversion limits. The site is supported by advertising.
Are my files uploaded to a server?
No. The conversion runs entirely inside your browser using WebAssembly, so your files never leave your device — that is what makes it instant and private.
Does it work on Windows, Mac, iPhone and Android?
Yes. Anything with a modern browser works: Windows, macOS, Linux, Android and iOS. No software installation is required.
What about special characters and non-English text?
Everything is handled as UTF-8. When you export CSV for Excel, a UTF-8 BOM is included automatically so Chinese, Japanese, Korean and accented characters display correctly on both Windows and macOS.
Is my data safe here?
Yes. The conversion is plain JavaScript running in your tab: the data is parsed and re-serialized in memory, never sent anywhere, and disappears when you close the page.
Are formulas, styles or multiple sheets converted?
No — this conversion extracts the data itself into XLS. Formulas are exported as their current values, styling is not carried over, and multi-sheet workbooks convert sheet by sheet. For full fidelity between spreadsheet formats, exchange within the same tool family.