How to Split a Large CSV File into Smaller Files

Excel stops at about one million rows, and many tools limit file size. Split the file instead.

Why split. Excel opens about 1,048,576 rows per sheet, so a bigger CSV is cut off without a clear warning. Many import tools and email systems also limit file size. Smaller parts are easier to open, check and upload.

Three ways to split. By rows: choose how many rows each file gets, for example 100,000. By equal parts: choose how many files you want and the rows are divided evenly. By a column value: you get one file per value of a column, such as one file for each country or each month. The header row is kept in every part.

Output format. You can save the parts as CSV, JSON, Excel or Parquet, and download them all as one ZIP. Parquet is a good choice when the parts will be analyzed by a tool such as DuckDB or Spark, because the files are much smaller.

Limits. The file is read in your browser, so the limit is your computer memory. Files up to about 100 MB usually work. The tool stops at 500 parts at a time, so choose a larger number of rows if you see that message. Nothing is uploaded.

Open the Merge or Split Files

Related tool pages

  • Combine Multiple CSV Files into One: Combine many CSV files into one file in your browser. Add a source_file column, mix in Excel or JSON files, and download CSV, Excel or Parquet. Free.
  • Merge Parquet Files into One: Merge several Parquet files into one Parquet, CSV or Excel file in your browser. No code and no upload. Free, with a source_file option.
  • Split a CSV File into Parts: Split a CSV into smaller files by number of rows, number of parts or the value of a column. Download them as one ZIP. Free, in your browser.
  • Split a Large CSV into Smaller Files: Split a large CSV into smaller files so Excel or an import tool can open them. Choose rows per file and download all parts as a ZIP. Free, no upload.
  • Split a Parquet File into Parts: Split a Parquet file into smaller Parquet, CSV or Excel files by rows, equal parts or a column value. Free, in your browser, nothing uploaded.

How to use the Merge or Split Files: step by step

  1. Open Merge or Split Files and choose Split.
  2. Load the file.
  3. Choose rows, equal parts or a column.
  4. Download the ZIP.

When to use the Merge or Split Files

  • Open a huge export in Excel
  • Meet an upload size limit
  • Share one file per region or per month
  • Break a Parquet file into parts

Example

Input: jan.csv + feb.csv + mar.csv

Output: merged.csv, 3 files in one

Frequently asked questions

Can I merge different formats?

Yes. You can mix CSV, JSON, Excel and Parquet files. They are read, stacked one after another and saved in the format you choose.

How can I split a file?

Choose rows per file, a number of equal parts, or one file per value of a column. You download all parts as one ZIP, in CSV, JSON, Excel or Parquet.

What if the files have different columns?

All columns are kept. Cells for a column that a file does not have are left empty, and the tool lists those columns so you can check.

Can I merge CSV and Parquet files together?

Yes. You can mix CSV, JSON, Excel and Parquet files. They are stacked in the order you add them and saved in the format you choose. Columns missing in some files are left empty.

Tip: Splitting by a column is the quickest way to give each team its own file.