Guide · Split
Split a large CSV file into multiple files
An import that refuses more than 50,000 rows, a spreadsheet that stops at 1,048,576, a colleague who can't open 2 GB: the file has to be cut. Here is how to split it cleanly, with the header row in every piece, without installing software and without uploading the file to a server.
In short
Open CSV Géant, choose your file, then under “Split” pick one of three options: files that open in Excel, a number of rows per file, or a number of equal-size files. Every output file starts with the header row. The file is read by your browser, on your computer.
Three ways to split
| Option in the tool | What it produces | Typical need |
|---|---|---|
| Files that open in Excel | Files of at most 1,048,575 data rows, plus the header row | Opening all the data in Excel, whose worksheet stops at 1,048,576 rows (details) |
| N rows per file | Files of N data rows (the last one holds the remainder) | An import with a row cap (CRM, email tool, e-commerce back office), batch uploads |
| N equal-size files | Up to N files (1,000 at most) with the same number of rows; only the last one, which gets the remainder, is slightly shorter | “Split a CSV file in half”, sharing work between several people |
Output files are named your-file-partie-001.csv, -partie-002.csv and so on (“partie” is French for “part”). They are written in UTF-8 with a BOM (the marker that lets Excel recognise accented characters), with the delimiter you choose: comma (the default when the interface is in English), semicolon, or tab.
For equal parts, the tool reads the file twice: a first pass counts the rows, the second writes the files.
Step by step
- Open the tool in Chrome or Edge, on a computer.
- Choose the file (.csv, .tsv or .txt) or drop it on the drop zone. It is not uploaded: the browser reads it in 8 MB chunks.
- Check the preview. The encoding (UTF-8, Windows-1252…) and the delimiter are detected automatically and the first 100 rows are shown. If the columns look wrong, change the delimiter in the list.
- Optional: count the rows with “Count all rows”, to know how many files you will get.
- Under “Split”, choose the option you need and enter the number of rows or files.
- Optional: clean up at the same time. In the same pass you can filter rows, remove duplicates, sort, and keep only some columns.
- Choose the destination. “Download” is fine up to about 1 GB of output; above that, “Write directly to a folder” (Chrome, Edge) writes the files as it goes.
- Click “Export”, then download the files one by one or with “Download all”.
Why not split, PowerShell or Python?
On Linux and macOS, split -l 100000 file.csv is very fast, but it counts raw line breaks: it does not repeat the header and it can cut a record in two when a quoted field contains a line break (a two-line address, for example). Scripts in PowerShell or Python can do it properly, if you are comfortable writing and running one.
CSV Géant parses the CSV like a spreadsheet does (doubled quotes, line breaks inside quotes): a data row is never cut across two files, and nothing needs to be installed.
What was measured
On a laptop (AMD Ryzen 5 4500U, 16 GB RAM, Windows 11, Chrome 154, automated test), a 2.22 GB file with 22 million rows was deduplicated and split into 21 Excel-sized files written to a folder in 102.2 s and 106.9 s (two runs). Timings depend on your machine.
Free or Pro
- Free: preview and row count with no size limit; split, filter, deduplicate and sort with at most 100,000 exported rows per operation. Example: splitting into files of 50,000 rows produces the first two files, and the tool tells you how many rows the full result would contain.
- Pro, €29 paid once: unlimited exported rows, in the browser where you enter the licence key emailed by Gumroad. No subscription.
Limits, honestly
- Browsers: tested in Chrome only. Edge uses the same engine but is not tested; Firefox and Safari are not tested. Writing to a folder only exists in Chrome and Edge.
- No split by column value (one file per country, per customer…): use the filter (for example “country equals US”) and export once per value.
- Sorting: if you sort in the same pass, the result is kept in memory, 3 million rows or 600 million characters at most.
- Above 2.22 GB, the streaming read has no size-dependent state, but nothing has been measured yet.
- CSV output only, no .xlsx file.
- A single record over 16 MB (usually an unclosed quote) stops processing with a message.
Frequently asked questions
How do I split a CSV file in half?
Choose “equal-size files” and enter 2. Both files get the same number of rows, give or take one (the second has one row less if the total is odd), and each starts with the header row.
Is the header repeated in every file?
Yes, as long as “1st row = headers” is ticked (it is by default). Untick it if your file has no header: no row will be repeated.
Is my file uploaded to a server?
No. It is read and split by your browser, on your computer. Once the page has loaded you can disconnect from the internet: splitting still works.
Can I split a CSV online for free?
Yes, up to 100,000 exported rows per operation, with no account and nothing to install. Unlike most online splitters, your file never leaves your computer.
Try it now
No account, and your file stays on your computer. No file at hand? The tool can generate a 2-million-row sample.