What a CSV file is and why you might need one

A CSV file is a plain-text spreadsheet that uses commas to separate columns. When you save an Excel spreadsheet as CSV, you convert it from Excel's native format (.xlsx) into a simpler format that almost any program can open — including Google Sheets, Apple Numbers, older versions of Excel, and many data analysis tools.

You need CSV when you're moving data between different programs, uploading information to a website, or sharing a spreadsheet with someone who doesn't have Excel. CSV strips away formatting like colors, fonts, and merged cells, keeping only the raw data and structure.

Key Takeaways

  • Open your spreadsheet in Excel, then click File > Save As to access the format options.
  • Choose "CSV (Comma delimited)" from the file type dropdown — this is the standard CSV format that works everywhere.
  • Excel will warn you that some formatting will be lost; click "Yes" to proceed with the save.
  • The file will save with a .csv extension, and you can open it again in Excel or any other spreadsheet program.
  • If your data contains commas within cells, CSV may split that data incorrectly — test the file after saving to confirm it looks right.

Step-by-step: saving your spreadsheet as CSV

Open the Excel file you want to convert. Click the File menu in the top left corner, then select Save As. A dialog box will open showing your current file name and location.

In the "Save as type" dropdown (on Windows) or "File Format" dropdown (on Mac), scroll down and select CSV (Comma delimited). This is the most common CSV format. You'll see other CSV options like "CSV (Macintosh)" or "CSV (MS-DOS)" — use the standard "Comma delimited" unless you have a specific reason not to.

Give your file a new name if you want, or keep the existing name. Excel will automatically add the .csv extension. Click Save. A popup will appear warning that the file may contain features that are not compatible with CSV format. Click Yes to proceed. Your file is now saved as CSV.

What happens to your formatting when you convert to CSV

CSV keeps your data but removes almost everything else. Colors, bold text, italics, cell borders, and background shading all disappear. Merged cells are unmerged. Charts, images, and formulas are lost — only the calculated values remain.

If your spreadsheet has multiple sheets, only the active sheet (the one you're currently viewing) will be saved as CSV. The other sheets are not included. If you need all sheets as CSV, you'll need to save each one separately.

Dates and numbers may display differently in CSV depending on your computer's regional settings. A date that shows as "3/15/2024" in Excel might appear as "15/3/2024" in CSV if your system uses a different date format. Open the CSV file after saving to verify that dates and numbers look correct.

When CSV doesn't work well for your data

If your cells contain commas, CSV will treat those commas as column separators and split your data into extra columns. For example, a cell containing "Smith, John" will become two columns: "Smith" and "John". When you open the file, the data will be misaligned. Test your file after saving by opening it in Excel or another program to check that all data is in the right columns.

If your data includes line breaks within cells, CSV may not preserve them correctly. Special characters like quotes, tabs, or symbols can also cause problems depending on the program you're opening the file in. For these situations, you might need a different format like .xlsx or .txt, or you may need to clean up your data before converting.

Very large spreadsheets (over 1 million rows) may not open in all CSV readers. Excel itself can handle CSV files with over 1 million rows, but some older programs or web tools cannot. If you're uploading to a website, check the site's file size or row limits before saving.

Opening a CSV file you've already saved

Double-clicking a CSV file usually opens it in Excel automatically. The data will appear in a spreadsheet view, and you can edit it the same way you would edit an .xlsx file. However, if you make changes and save, Excel will ask whether you want to keep the CSV format or convert back to Excel format — choose based on where the file needs to go next.

If you want to open a CSV file in a different program, right-click the file, select "Open with," and choose the program you want. Google Sheets, Apple Numbers, LibreOffice Calc, and many other programs can open CSV files directly. Some programs may ask you to confirm how to interpret the columns — usually the default settings work fine.

Saving back to Excel format if you change your mind

If you've saved a file as CSV and later decide you need it in Excel format again, open the CSV file in Excel, then go to File > Save As. In the file type dropdown, select Excel Workbook (.xlsx) instead of CSV. Your formatting and multiple sheets will not come back — they were lost when you first converted to CSV — but the data will be in Excel format.

To avoid losing formatting, keep a copy of your original .xlsx file before converting to CSV. That way you have both versions: the formatted Excel file for editing and sharing with others, and the CSV version for uploading or importing into other programs.

Frequently Asked Questions

Can I save multiple sheets as one CSV file?

No. CSV format supports only one sheet at a time. If you have multiple sheets, you must save each one separately as its own CSV file. Open each sheet, go to File > Save As, and save it with a different name so the files don't overwrite each other.

What's the difference between CSV and other formats like TSV?

CSV uses commas to separate columns; TSV uses tabs. Both are plain-text formats that work in most programs. Use CSV unless the program you're uploading to specifically asks for TSV or another format. Most programs default to CSV.

Will my formulas be saved in the CSV file?

No. CSV saves only the results of formulas, not the formulas themselves. If a cell contains =SUM(A1:A10), the CSV file will contain only the number that formula calculated. If you need the formulas, keep the original .xlsx file.

Why does my CSV file look weird when I open it in Excel?

This usually happens if your data contains commas or special characters. Open the file in a text editor like Notepad to see the raw data and check whether commas in your cells are causing columns to split incorrectly. If they are, you may need to clean up your data or use a different format.

Can I edit a CSV file and save it again?

Yes. Open it in Excel, make your changes, and save. Excel will ask whether you want to keep the CSV format — click "Yes" to save it as CSV again, or "No" to convert it back to .xlsx. Either way, your edits will be preserved.