What Excel Format Should I Use?

When you go to save an Excel file, you're faced with a dropdown list of format options that can be a little overwhelming if you don't know what each one does.

Contents:

1. Quick Answer

2. The Most Common Excel Formats

2.1 XLSX (The Default)

2.2 XLSM (When You Have Macros)

2.3 CSV (When You Need Plain Data)

2.4 XLS (For Legacy Compatibility)

3. Format Summary Table

Quick Answer

For almost everyone, almost all the time, save as .xlsx. It's the modern Excel format, supported everywhere, and has no meaningful downsides. The only reasons to use something else: you have macros (use .xlsm), you need to share raw data with another system (use .csv), or someone is stuck on Excel 2003 or earlier (use .xls).

The Most Common Excel Formats

XLSX (The Default)

XLSX is the standard Excel workbook format introduced in Excel 2007. It handles multiple sheets, formulas, charts, formatting, pivot tables, basically everything you'd normally do in Excel.

If you hit Save and don't change anything, this is what Excel saves as. That's intentional. It's the right choice for the vast majority of workbooks.

One thing to know: XLSX cannot store VBA macros. If you record or write a macro and try to save as .xlsx, Excel will warn you and strip the macro out.

XLSM (When You Have Macros)

XLSM is identical to XLSX, with one difference: it can store VBA macros. The "M" stands for macro-enabled.

If your workbook contains any macros (whether you wrote them yourself or inherited the file), you need to save as .xlsm or the macros will be lost. Excel will prompt you about this automatically, so you won't accidentally lose code without a warning.

CSV (When You Need Plain Data)

CSV (Comma Separated Values) saves only the values from a single sheet, with no formatting, no formulas, and no multiple tabs. It's a plain text file, readable by virtually any software.

Use .csv when you're exporting data to another tool, uploading to a database, or sharing with someone who doesn't use Excel. If you're curious about how CSV and Excel files differ at a deeper level, the Excel vs CSV breakdown is worth a read.

One caveat: because CSV strips everything down to raw values, you'll lose any formatting or formulas when you save this way. Keep a copy of the original .xlsx if you need to go back.

XLS (For Legacy Compatibility)

XLS is the old Excel format, used by Excel 97 through 2003. It has a row limit of 65,536 rows (compared to 1,048,576 in modern Excel) and doesn't support newer functions.

The only reason to save as .xls today is if you're sharing a file with someone using a very old version of Excel. In practice, this is rare. Modern Excel can open .xls files just fine, so there's almost never a reason to save in this format unless someone specifically asks for it.

Format Summary Table

There are other formats in the Save As dropdown (like .xlsb for binary, or .pdf for publishing), but the four above cover nearly every real-world scenario. When in doubt, .xlsx is your answer.