CSV Splitter (Split a CSV into Smaller Files)

Many systems refuse large imports — a mailing tool that accepts 5,000 contacts at a time, a spreadsheet that slows to a crawl, an upload form with a size limit. This splitter cuts a CSV or Excel file into smaller CSV files: a fixed number of rows per file, a number of equal parts, or one file per value of a column (one file per region, per store, per month). The header row is repeated in every part, and all parts download together as a ZIP.

How to use this tool

1. Choose the CSV, TSV or Excel file (first sheet), or paste CSV.
2. Choose how to split: every N rows, into N parts, or by a column's values.
3. Set N, or the column name or number.
4. Pick the delimiter and whether to add a UTF-8 BOM for Excel.
5. Download the parts — all of them as one ZIP.

Formula

parts = ⌈data rows ÷ rows per file⌉ · rows per part = ⌈data rows ÷ parts⌉

The header row is not counted as data and is copied to the top of every file. In "by values" mode rows keep their original order inside each file, files appear in the order the values first occur, and the value becomes part of the file name (characters that file systems forbid are replaced by _). Fields are re-quoted according to RFC 4180, so commas, quotes and line breaks inside values survive.

Example

A file with a header and 5 data rows split every 2 rows gives 3 files: data_001.csv (rows 1–2), data_002.csv (rows 3–4) and data_003.csv (row 5), each starting with id,region. Split by region instead, it gives data_north.csv (2 rows), data_south.csv (2 rows) and data_east.csv (1 row).