A CSV with more rows than Excel can hold: how to split it into several files on a Mac

Q: First: is it really over the limit?

Check the row count before you split. In Terminal, wc -l yourfile.csv counts lines. That equals the number of records only when no field contains a line break inside quotes. If your file has multi-line text fields, the line count will be higher than the record count.

By Kayabyte · Last updated 11 November 2026

Short answer: a worksheet in Excel holds at most 1,048,576 rows and 16,384 columns (Microsoft’s specifications page, checked 11 November 2026). A CSV with more rows than that cannot fit on one sheet, so the fix is to cut it into parts that each fit, with the header row in every part. You can do it in Terminal for free if the file is simple, or with Gridhand’s Convert, which writes the whole CSV into one .xlsx workbook and continues on further sheets with the header row repeated, so nothing is cut.

First: is it really over the limit?

Check the row count before you split. In Terminal, wc -l yourfile.csv counts lines. That equals the number of records only when no field contains a line break inside quotes. If your file has multi-line text fields, the line count will be higher than the record count.

Free way: Terminal

split -l 500000 yourfile.csv part_ cuts the file into pieces of 500,000 lines. Two things to know:

Only the first piece has the header row. You would need to add it to the others yourself.
It cuts on lines, so a quoted field that contains a line break can be cut in half.

For a plain export without those problems this is fine. For anything else, check the pieces before you trust them.

Gridhand way

Gridhand is a Mac app we make. It reads .csv, .tsv, .xlsx, .xlsm and delimited .txt files, does not need Microsoft Excel, and is not an Excel add-in. A CSV goes through its Convert tool: Split, Merge and the other tools work on .xlsx workbooks.

Open Gridhand, choose Convert and drop in the CSV.
Read the preview. Previews read at most the first 20,000 rows of a sheet and say so; the run itself reads every row.
Choose an output folder and run. The result is a new .xlsx workbook; your original CSV is never modified.

Excel holds 1,048,576 rows per sheet, so a longer CSV continues on further sheets in the same workbook, with the header row repeated on each, and the report says how many sheets it used. Nothing is cut.

If you want separate files instead of sheets, run Split on that workbook with the one-file-per-sheet option. Each file then has its own header row.

Gridhand works offline, with no account and no AI; nothing is uploaded. It is free to try: unlimited previews plus 2 free runs of any tool on up to 2 input files each. Gridhand Pro is USD 49 one time for 2 Macs, with one year of updates and a 30-day refund. macOS 15 or later. Download Gridhand.

We have not published timings for very large files, so try your own file on the free runs first.

After splitting

Splitting means each part is analysed on its own. If you need totals across all parts, add up the parts in a final step, or combine summaries rather than the raw rows. See how to merge Excel files on a Mac for combining files that fit.

Questions

What is the row limit in Excel? 1,048,576 rows by 16,384 columns per worksheet, according to Microsoft (checked 11 November 2026).

Does Gridhand repeat the header on every sheet? Yes. When a converted CSV runs over several sheets, the header row is repeated on each.

Does converting change my original CSV? No. Results are new files in a folder you choose.

Does Gridhand open .numbers files? No. .xls and .numbers files are not supported, and password-protected workbooks are refused.

Microsoft and Excel are trademarks of the Microsoft group of companies. Gridhand is made by Kayabyte and is not affiliated with or endorsed by Microsoft.