Guide
Your CSV is too large for Excel? Here's why — and 4 ways to open it
Excel stops at 1,048,576 rows. Learn why big CSV files get cut off, how to tell if you lost data, and four practical ways to open or split them.
Updated 1 October 2026 4 min read
You double-click a CSV export from your CRM, shop or bank, Excel thinks for a while, and then shows “File not loaded completely”. Or worse, it opens without complaint and you only notice later that the totals don't match. Both have the same cause: the file has more rows than an Excel worksheet can hold.
The hard limit: 1,048,576 rows
Every Excel worksheet is limited to 1,048,576 rows and 16,384 columns. That has been true since Excel 2007 and it is the same in Microsoft 365 today. When a CSV is longer, Excel loads the first 1,048,576 lines (including the header) and silently drops the rest.
A CSV file itself has no such limit — it is just text. Exports from analytics tools, e-commerce platforms or data warehouses easily reach several million rows.
How to check whether you lost data
- Press
Ctrl+↓in the first column. If you land exactly on row 1,048,576, the file was cut. - Compare the file size with what you see: a 300 MB CSV with “only” a million rows is a red flag.
- Check the source: most export screens tell you how many rows were exported.
Fix 1 — Split the CSV into Excel-sized parts
The simplest fix: cut the file into several smaller CSVs, each under the limit, with the header repeated at the top of every part. You can then open each part normally.
On macOS or Linux, the split command does this, but only the first part keeps the header row:
split -l 1000000 export.csv part_A tool built for the job keeps the header in every part and copes with quoted values that contain line breaks.
Fix 2 — Convert to an Excel workbook with several sheets
If you want a single file to send to a colleague, convert the CSV to .xlsx and continue on Sheet 2, Sheet 3 and so on whenever the limit is reached. Each sheet stays under 1,048,576 rows.
Fix 3 — Load it into Excel's Data Model (Excel for Windows)
Excel for Windows can analyse more than a million rows without putting them on a sheet. Go to Data → Get Data → From File → From Text/CSV, then choose Load To…, select Only Create Connection and tick Add this data to the Data Model. You can then build PivotTables on the full file. You can't scroll through the rows, though — it is for summaries, not for browsing.
Fix 4 — Use a tool made for big data
Databases and languages like Python (pandas) handle tens of millions of rows easily — if you are comfortable writing code. For everyone else, a viewer that can scroll, search and sort millions of rows without Excel's limit is the missing piece.
Coming soon: a huge-CSV viewer that runs in your browser
Open, search and sort millions of rows — still with nothing uploaded.
Which fix should you pick?
| You need to… | Best option |
|---|---|
| Open and edit the data in Excel | Split the CSV |
| Send one Excel file to someone | CSV to Excel with several sheets |
| Build totals and PivotTables on everything | Excel's Data Model (Windows) |
| Browse, search and filter all rows | A big-data viewer |
Frequently asked questions
Does Microsoft 365 have a higher row limit?
No. Every version of Excel since 2007, including Microsoft 365, stops at 1,048,576 rows and 16,384 columns per worksheet.
Can Google Sheets open the file instead?
Only if it is small enough: Google Sheets allows 10 million cells per spreadsheet, so a CSV with 10 columns tops out at about one million rows. It also requires uploading the file to Google.
Will splitting or converting change my data?
It shouldn't. A good splitter copies every value as it is and only adds the header to each part. Check that the total number of rows across the parts matches the original.