A CSV splitter for files too big to open
Excel stops at 1,048,576 rows per sheet, and many upload forms, e-mail servers and import screens cap a file at a few megabytes. This CSV splitter cuts one large CSV or TSV file into smaller ones that do open: a fixed number of data rows per file, a set number of equal files, files under a size limit, or one file for each value in a column — one per region, month or branch. The header row is copied to the top of every part, so each file works on its own.
The split is exact. Rows are copied byte for byte, quoted fields that contain commas or line breaks stay whole, and the parts joined back together give the original data. Files are read in pieces, so a multi-gigabyte export that Excel and Notepad refuse to open can still be split on an ordinary laptop.
Everything runs in your browser. The file is never uploaded, which matters for customer lists, bank statements and order exports.
How to split a CSV file
- Drop your CSV, TSV or TXT file on the box, or click it to choose one. The tool reports its size, text encoding and delimiter. A 25-row sample is loaded so you can try the options first.
- Choose Split by: rows per file (press Excel limit for 1,048,575 data rows plus the header), number of files, largest file size in MB, or a column value.
- Keep First row is a header ticked to repeat the column names in every part. Tick the BOM option if Excel will open the files and they contain ₹, accents or non-Latin text.
- Press Split CSV. Files up to 25 MB update instantly as you change options; bigger files show a progress bar.
- Click a row to preview the start of that part, download any single part, or press Download all (ZIP).
CSV Splitter features
Four ways to split
Rows per file, number of equal files, maximum size in MB (for upload and e-mail limits), or one file per distinct value of any column.
Header in every file
The first line is repeated at the top of each part, so every file imports with the right column names.
Quote-aware and exact
Line breaks inside quoted fields never cut a record in two. Rows are copied unchanged; only a missing final line break is added.
Big files, low memory
The file is streamed in chunks and parts are stored as browser blobs, so files far larger than Excel’s limit can be split.
Encodings handled
UTF-8 with or without BOM, and Windows-1252 exports from older software, which are converted to UTF-8.
One ZIP or single files
The ZIP is built in your browser with a CRC-32 checksum for every entry; each part can also be downloaded on its own.
Which split to choose
Microsoft lists the worksheet limit as 1,048,576 rows by 16,384 columns (“Excel specifications and limits”, checked 30 October 2026). One row holds the header, so 1,048,575 data rows fill a sheet. Excel and Google Sheets can still be slow long before that, so 100,000 or 500,000 rows per file is often more comfortable.
| You need to… | Split by | Example |
|---|---|---|
| Open the data in Excel | Rows per file → Excel limit | A 3.2 million-row export becomes 4 files |
| Share the work between people | Number of files | 4 files for 4 people, rows shared out evenly |
| Upload to a site with a size cap | Maximum file size | Parts under 10 MB for an e-mail or import limit |
| Send each branch its own rows | Column value | One file per region, state, salesperson or month |
How the split works
- The file is decoded as UTF-8; if that fails, as Windows-1252. The delimiter (comma, semicolon, tab or pipe) is detected from the first lines, or you can set it.
- A record ends at a line break that is not inside double quotes, following RFC 4180, so
"Gift wrap⏎with card"stays one row. CRLF, LF and old Mac CR line endings are all kept as they are. - “Number of files” reads the file twice: once to count rows, once to split, giving equal parts with the remainder in the last file.
- “Column value” keeps rows in their original order inside each file and names the files after the values, for example
orders-North.csv. Up to 2,000 different values and 10,000 files are allowed. - Blank lines and rows that are only delimiters can be skipped. Rows longer than the size limit still go into a file of their own.
Related tools
To put parts back together, or combine monthly exports, use the CSV Merger. For Excel workbooks with several sheets, use the Excel Splitter. To look inside one part, open it in the CSV Viewer.
CSV Splitter FAQ
How do I split a CSV file that is too big for Excel?
Drop the file here, choose “Rows per file”, press Excel limit and then Split CSV. Each part holds at most 1,048,575 data rows plus the header, so it opens in one Excel sheet.
Does every part keep the header row?
Yes, as long as “First row is a header” is ticked. Untick it for files without column names; then rows are split as they are.
Can I split a CSV by a column value?
Yes. Choose “Column value” and the column — region, state, month, team — and you get one file per value, named after it, with rows in their original order.
Is there a file size limit?
Files over 25 MB are streamed in pieces, so the limit is your device’s memory and the 4 GB ZIP limit. For very large files, download the parts one by one.
Is my data uploaded?
No. The file is read and split by JavaScript in your browser, and the ZIP is created on your device.