Split a large CSV file
Break a huge CSV into parts that Excel can open, a mailing platform will import or an upload form will accept. Every part gets the header row, rows are never cut in half, and the whole job runs in your browser, so the export never leaves your device.
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Results
How to split a large CSV file
- Drop the CSV file you want to split.
- Enter how many rows each part should contain.
- Choose whether to repeat the header row in every part (recommended).
- Run and download the numbered parts, individually or as one ZIP.
Why big CSV files need splitting
A CSV with a million rows is normal for a database export and useless for most of the places it needs to go. Excel stops at 1,048,576 rows and becomes sluggish long before that. Google Sheets has a cell limit. Mailing platforms cap imports at a few thousand or tens of thousands of contacts per upload. Web forms reject files over a size limit. Email attachments have their own caps. Splitting the file into evenly sized parts, each with its own header row, solves all of these.
How the tool splits
Drop the file and choose how many rows each part should contain. The header row is detected and copied to the top of every part, so each file opens and imports correctly on its own. Rows are never broken mid-way, even when a field contains line breaks inside quotes, because the file is parsed properly rather than cut at byte positions. The parts are numbered (customers-01.csv, customers-02.csv and so on) and can be downloaded individually or together as a ZIP.
Choosing the row count
| Destination | Rows per part |
|---|---|
| Excel, comfortable working size | 100,000 to 250,000 |
| Google Sheets | 50,000 to 100,000 depending on column count |
| Mailchimp, Klaviyo and similar imports | Check the platform limit; often 10,000 to 50,000 |
| Upload forms with a size cap | Divide the file size by the cap and add a margin |
| Sharing chunks with several people | Whatever divides the work evenly |
Large files in the browser
The file is processed in your browser's memory. Files of a few hundred megabytes are fine on a laptop; on a phone, very large files may run out of memory. Nothing is uploaded, which is the point: exports like these usually contain customer or financial data.
Putting it back together
If you later need the whole file again, the merge CSV tool joins the parts back into one, keeping a single header row.
Typical uses
- Breaking a database export into pieces Excel can open.
- Staying under a mailing platform's import limit.
- Splitting a product feed for a marketplace that caps upload size.
- Distributing a large list among a team for manual checking.
Frequently asked questions
Is the file uploaded?
No. Splitting happens in your browser memory and nothing is sent anywhere.
Does every part get the header?
Yes, when the option is on. Each part then opens and imports correctly on its own.
Can a row be cut in half?
No. The file is parsed properly, so quoted fields containing line breaks stay intact and parts always break between rows.
How big a file can it handle?
Files of a few hundred megabytes are fine on a laptop. A phone may run out of memory on very large files.
Your files never leave your device
Every tool on Squishly Tools is 100% free and runs entirely inside your browser. Your images and documents are processed on your own computer and are never uploaded to a server. There are no accounts, no watermarks and no catch.