What is the difference between XLS and CSV?

XLS is the pre-2007 Excel binary workbook format. It is still emitted by legacy systems and older export routines, and remains readable by current spreadsheet software, though support is being phased out in favour of XLSX. CSV is a plain-text table format: one row per line, fields separated by commas, usually with a header row. It is the most widely supported data format there is, readable by every spreadsheet, database and analytics tool.

Will I lose anything converting XLS to CSV?

Some things, yes. XLS carries formatting, multiple sheets and formulas, and CSV has no way to represent any of it. The values themselves come across intact; the structure around them does not.

Anything to watch out for with CSV?

CSV has no formal specification, only a convention (RFC 4180). Delimiters, quoting and line endings vary between producers. Leading zeros and long numeric strings are frequently mangled by spreadsheet applications on import — a ZIP code of 01234 becomes 1234.

What happens to formulas?

Formulas are exported as their last computed values. The formula text itself is not preserved in CSV, because the format has no way to represent it.

What if my workbook has multiple sheets?

CSV is a single-table format, so only the first sheet is exported. If you need another sheet, reorder the workbook first or export each sheet separately.

What should I know about starting from XLS?

XLS is the pre-2007 binary format, capped at 65,536 rows and 256 columns per sheet, and increasingly deprecated by the software that reads it. More broadly: XLS is the legacy Excel binary format, the default until Office 2007. It is still produced by older enterprise systems and by export routines nobody has revisited in fifteen years.

When is CSV the right choice?

CSV suits: moving tabular data between tools that share nothing else; bulk import and export; large flat datasets where JSON's repeated keys would dominate. It is the wrong choice when nested or hierarchical data.

Is there a file size limit?

No hard limit — the constraint is your browser's memory. Files under 50MB convert in a few seconds. Larger files work but take longer, and a browser tab typically has 250-500MB to play with, so very large batches are better split into smaller groups.

Does this work on mobile?

Yes. The drop zone falls back to your phone's file picker, and the conversion runs on-device exactly as it does on desktop. Large files are slower on a phone because there is less CPU and memory available, but nothing about the workflow changes.

Convert XLS to CSV

Export a XLS sheet to CSV. One sheet, computed values, no formatting — the format every tool imports. Free, in your browser, no upload.

Drop spreadsheet files to convert

XLSX, XLS, ODS, CSV

Files stay on your device. Open DevTools' Network tab to verify.

Overview

Why convert XLS to CSV

XLS is a binary format — you cannot open it in a text editor or diff it in version control. Converting to CSV gives you something readable and greppable, at the cost of XLS's type information and structure.

Comparison

XLS vs CSV: what actually differs

XLS compared with CSV across encoding, fidelity, file size and support.
Attribute	XLS	CSV
Full name	Excel Binary Interchange Format	Comma-Separated Values
Encoding	Binary	Text — editor-readable
What it preserves	Multiple sheets and formulas, with older limits	Flat only — no nesting, no types, no formatting
Typical size	Larger than XLSX for the same content — no ZIP container	Very compact for tabular data
Support	Read by Excel, LibreOffice and Google Sheets; increasingly deprecated.	Universal. Every spreadsheet, database and BI tool imports it.

How to

How to convert XLS to CSV

01
Drop your XLS file
Drag one or more XLS files onto the drop zone above, or click to browse. Files stay on your device — there is no upload step.
02
Convert to CSV
convert.now parses the XLS and writes it out as CSV in a Web Worker, so the page stays responsive even on large files. Nothing is sent anywhere.
03
Download the result
Download the CSV file, or a zip of all of them for a batch. Filenames are preserved, with the extension changed to .csv.

Why here

Why convert.now

Private
Files stay in your browser. No upload step. Nothing for anyone to see.
Fast
No queue, no upload wait. Conversion starts the moment you drop a file.
Free
No ads. No file-count limit. No sign-up wall. Just the converter.

FAQ

XLS to CSV: common questions

No. The XLS to CSV conversion runs entirely in your browser. Files never leave your device, and there is no server involved in the conversion at all. Open DevTools' Network tab and run a conversion if you want to confirm it — you will see the page and its code load, and no request carrying your file.

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Last updated 27 August 2026

Why convert XLS to CSV

XLS vs CSV: what actually differs

How to convert XLS to CSV

Drop your XLS file

Convert to CSV

Download the result

Why convert.now

XLS to CSV: common questions

Related XLS converters