CONVERT XLS → CSV (XLS to CSV)
Fast, secure XLS to CSV conversion. No registration required.
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HOW TO CONVERT XLS → CSV
Upload the XLS
Drop your file into the browser uploader. We transfer over HTTPS and queue the conversion.
Convert through libreoffice
Our libreoffice-based pipeline reads the XLS, applies the right decoder and emits a faithful CSV.
Download the CSV
Grab the result when it lands. Both files delete automatically within two hours — nothing lingers on our servers.
XLS is a binary compound document format (BIFF — Binary Interchange File Format) that Microsoft introduced with Excel 2.0 in 1987 and retired with Excel 2007 in favor of XLSX. Beyond raw cell values, an XLS workbook carries VBA macros, named ranges, pivot table definitions, conditional formatting rules, custom number formats, multiple worksheets, embedded charts, and cell-level metadata such as comments and formula strings. CSV is a plain-text interchange format with no schema of its own: one row per line, fields delimited by a separator character (comma by default, though regional Excel installs often write semicolons), and no encoding of anything beyond the content of individual cells. The practical motivation for XLS-to-CSV is almost always pipeline integration: Python pandas, PostgreSQL COPY, SQLite .import, MySQL LOAD DATA, R read.csv, and most ETL tools accept CSV directly but require a third-party library to parse binary XLS. Stripping the binary container to plain text removes the dependency on the BIFF parser entirely.
Why convert XLS to CSV
Databases, data pipelines, and command-line tools rarely speak BIFF. A PostgreSQL COPY command, a pandas read_csv call, or a shell awk script can consume CSV with zero dependencies, whereas reading XLS requires xlrd (which dropped XLS support after version 1.2.0 in 2020) or a COM automation layer on Windows. CSV is also version-neutral: there is no BIFF5 versus BIFF8 ambiguity, no encryption flag to strip, and no need to detect whether a file is actually an OLE2 compound document. For archival and regulatory use, plain-text CSV is auditable without proprietary software.
XLS vs CSV — Technical specifications
Side-by-side comparison of the technical details.
XLS
- MIME type
- application/vnd.ms-excel
- Max rows
- 65 536 (Excel 97-2003)
- Max columns
- 256 (A to IV)
- Container
- OLE Compound File
- Successor
- .xlsx (2007)
- MIME Type
- application/vnd.ms-excel
- Extension
- .xls
- Category
- Spreadsheets & Data
- Full Name
- Excel Spreadsheet (Legacy)
- Conversion Engine
- LIBREOFFICE
CSV
- MIME type
- text/csv
- MIME Type
- text/csv
- Extension
- .csv
- Category
- Spreadsheets & Data
- Full Name
- CSV (Comma-Separated Values)
- Conversion Engine
- LIBREOFFICE
- Specification
- RFC 4180 (informational)
- Typical separator
- Comma (;), semicolon, tab, pipe
- Typical encoding
- UTF-8, Windows-1252, ISO-8859-1
- Line endings
- LF (Unix), CRLF (Windows)
| Specification | XLS | CSV |
|---|---|---|
| MIME type | application/vnd.ms-excel | text/csv |
| Max rows | 65 536 (Excel 97-2003) | — |
| Max columns | 256 (A to IV) | — |
| Container | OLE Compound File | — |
| Successor | .xlsx (2007) | — |
| MIME Type | application/vnd.ms-excel | text/csv |
| Extension | .xls | .csv |
| Category | Spreadsheets & Data | Spreadsheets & Data |
| Full Name | Excel Spreadsheet (Legacy) | CSV (Comma-Separated Values) |
| Conversion Engine | LIBREOFFICE | LIBREOFFICE |
| Specification | — | RFC 4180 (informational) |
| Typical separator | — | Comma (;), semicolon, tab, pipe |
| Typical encoding | — | UTF-8, Windows-1252, ISO-8859-1 |
| Line endings | — | LF (Unix), CRLF (Windows) |
XLS vs CSV — Strengths and limitations
What each format does best, and where it falls short.
XLS Strengths
- Universal legacy — every Excel since 1997 opens .xls natively.
- Binary format is compact and loads quickly.
- Full support for formulas, charts, pivots, and VBA macros.
- Deep integration with every accounting and ERP system of the 1990s-2000s.
Limitations
- Row/column limits are ~64× smaller than modern XLSX.
- Macro-enabled variants are a notorious malware vector.
- Binary corruption often means total data loss.
CSV Strengths
- Universally readable — every spreadsheet, database, and programming language.
- Human-readable in any text editor.
- Stream-friendly — can process terabytes with constant memory.
- Git-friendly — clean diffs of row changes.
- Tiny overhead vs columnar data structures for simple data.
Limitations
- No standard — quoting, escaping, encoding, and separators vary wildly.
- No type information: 0042 might be an integer, a string, or an error.
- Leading zeros and large numbers often get mangled by Excel auto-conversion.
Quality & Compatibility
Only the active worksheet is exported per conversion pass — all other sheets in the workbook are silently discarded. Cell values are serialized as their displayed string: a date stored as a serial number (e.g., 45000) comes out as the formatted date string Excel would show (e.g., 2023-03-15), not the integer, provided the converter reads the format mask. Formulas are collapsed to their last-calculated result; the formula itself is lost. Number formats, fonts, colors, merged cells, comments, named ranges, charts, and VBA macros are entirely absent from the output. Boolean TRUE/FALSE, numeric precision beyond 15 significant digits, and any cell containing an Excel error value (#DIV/0!, #REF!) each need explicit handling or they become empty fields or literal strings. Character encoding defaults to UTF-8 in this converter; the original XLS codepage (often Windows-1252 in pre-2000 files) is transcoded automatically.
Tips for Best Results
- Choose which worksheet to convert before uploading if your XLS has multiple tabs — only one sheet can become one CSV file, and the converter uses the first sheet by default. Rename or reorder your sheets in Excel first if you need a specific one.
- Check your date columns after conversion. XLS stores dates as floating-point serial numbers with a format mask applied at display time. If the converter does not read that mask correctly, dates appear as integers like 44927 instead of 2023-01-02 — open the CSV in a text editor to verify before feeding it to a database loader.
- If your CSV will be imported into a locale that uses commas as decimal separators (German, French, Spanish Excel installs), verify the delimiter character in the output. Some XLS files produced by those locales already use semicolons internally, and a comma-delimited CSV will misalign numeric columns. Most import tools let you specify the delimiter explicitly.
Frequently Asked Questions
Yes. The free tier accepts files up to 25 MB without registration, email capture or watermarks; paid plans go up to 2 GB. Paid plans raise the size cap, enable batch conversions and provide a REST API for automation, but nothing on the free tier is quality-limited — the output is exactly the same as on any paid plan.
Uploads run over HTTPS, files are processed in isolated containers, and both the source XLS and the CSV output are auto-deleted within two hours. No account is required, file contents are never logged, and KaijuConverter does not use uploads for AI training. The paid plan adds a signable data-processing agreement for regulated workflows.
Most files finish in well under a minute. Small images and documents are typically ready in a few seconds; large video or audio files scale roughly with duration. Upload speed from your network is usually the dominant factor, not server time.
Excel Spreadsheet (Legacy)
Source formatXLS is the legacy binary format for Microsoft Excel 97-2003 spreadsheets. While superseded by XLSX, it remains common in archived data and older business systems.
CSV (Comma-Separated Values)
Target formatCSV is a simple text-based format for tabular data where values are separated by commas. It is the universal interchange format for data between spreadsheet applications, databases, and programming languages.
Common Use Cases
Share across platforms
Send CSV files to anyone without worrying about whether they have the right software for XLS.
Embed in documents
Drop CSV output into Word, Google Docs, PowerPoint, Notion or a website without conversion warnings.
Optimize size
CSV often produces smaller files than XLS for web, email and storage.
Archive & future-proof
Store in a widely-supported format that will still open on future operating systems without legacy plugins.
XLS vs CSV — Typical file sizes
Approximate file sizes for common scenarios.
- Simple budget (1 sheet) 30-60 KB
- Multi-sheet financial model 500 KB - 5 MB
- Data export with 65 000 rows 5-20 MB
- Contact export (1000 rows) 100–300 KB
- Analytics export (100k rows) 10–100 MB
- Large dataset (1M rows) 100 MB – 1 GB
Sensitive Documents, Scanned OCR, or 500+ Pages?
For legally sensitive archives that must never leave your local network, or multi-hundred page scanned PDFs needing optical character recognition, local document workstations ensure full compliance.
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High-throughput enterprise pipeline for files up to 2,048 MB, 50-file batches, ISO PDF/A, and priority processing.
Offline conversion for multi-hundred page contracts, spreadsheets, and local optical extraction.
High-accuracy legal OCR, certified PDF/A archiving, and compliant document redaction.
Related comparisons
See these formats side by side to understand which fits your use case best.
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