Excel Files List: Common Formats, Extensions, and Uses

The main Excel file types are .xlsx, .xlsm, .xlsb, and the older .xls format; Excel also uses templates such as .xltx and .xltm. Files such as .csv and .ods can be opened or saved by Excel, but they do not preserve every workbook feature, so the right choice depends on what the file needs to contain.

Common Excel file extensions at a glance

These extensions cover the formats most people encounter when opening, sharing, or saving spreadsheets:

.xlsx — The standard XML-based Excel workbook format. It stores sheets, formulas, formatting, charts, and many other workbook features, but it does not store VBA macros.
.xlsm — An XML-based workbook that can contain VBA macros. Use it when the workbook needs both modern Excel features and its embedded macros.
.xlsb — An Excel Binary Workbook. It supports worksheets and VBA macros and stores workbook data in a binary format rather than the XML package used by .xlsx and .xlsm.
.xls — The older Excel 97–2003 workbook format. It remains useful for some legacy systems, but has lower worksheet limits and can lose features created in newer Excel versions.
.xltx — An XML-based workbook template without VBA macros. It provides a starting layout for new workbooks.
.xltm — A macro-enabled workbook template, suitable when new workbooks need to inherit VBA code as well as a layout.
.csv — Comma-separated text data. It can represent a table of values, but not a complete Excel workbook with multiple sheets, formulas, and formatting.
.ods — The OpenDocument Spreadsheet format, used by applications such as LibreOffice Calc and supported by Excel for opening and saving spreadsheets.

An extension is the short suffix after a filename’s final period, such as Budget.xlsx. It indicates the file format, but changing the suffix by renaming a file does not convert its contents. Use Excel’s save or export options to create a different format.

How the main workbook formats differ

For ordinary work in Microsoft Excel for Microsoft 365 on Windows, .xlsx is usually the best default. It supports the capabilities most users expect, is widely compatible with current spreadsheet software, and avoids the macro-enabled status that can prompt extra security warnings. Its main limitation is that VBA code cannot be saved in an .xlsx workbook. If you try to save a macro-containing workbook as .xlsx, Excel warns that the macros will be removed if you continue.

Choose .xlsm when a workbook contains VBA that needs to remain available. The extension does not mean the file must contain macros; it means the format can store them. Macro-enabled files deserve additional care when they arrive from someone you do not know, because macros can run code. A trusted business process may require them, but a file extension alone does not establish that a workbook is safe.

The .xlsb format is another option for large or complex workbooks. Because it uses binary storage, a particular workbook may be smaller or open and save more quickly than its XML-based counterpart. Results depend on the workbook, however, so .xlsb is not automatically better for every file. Some external systems and tools handle .xlsx more readily, making it worth checking compatibility before choosing .xlsb for a shared deliverable.

The .xls format is mainly for compatibility with older software. Excel 97–2003 worksheets are limited to 65,536 rows and 256 columns, compared with 1,048,576 rows and 16,384 columns in current .xlsx worksheets. Saving a newer workbook as .xls can also remove or alter newer features. Use it only when a recipient or legacy application specifically needs that format, and review Excel’s compatibility warning before saving.

CSV, text, and other exchange formats

A .csv file is useful when the goal is to exchange plain tabular data with another program. It is text, not a full workbook: it generally represents one sheet at a time and does not preserve cell formatting, charts, multiple tabs, or Excel formulas as working formulas. A formula cell may be exported as its displayed value, depending on the export and application settings. If the recipient needs the workbook’s structure or calculations, send an .xlsx copy as well.

CSV files can also cause surprises because the comma is used as a field separator, while regional settings may use a different list separator. Text containing commas is normally enclosed in quotation marks by a proper CSV exporter. When opening a CSV directly, Excel may interpret dates, leading zeros, and long digit strings as numbers or dates. For example, an identifier such as 00127 may display as 127. Importing the data through Excel’s text import controls lets you specify column types and preserve identifiers as text.

Excel can also work with text formats such as tab-delimited files. These are similarly limited: they are useful for moving values, not for retaining a complete workbook. The .ods format is more workbook-like than CSV and can preserve sheets and formatting, but conversion between spreadsheet applications may change some features. If exact appearance, formulas, or advanced Excel functionality matter, keep a copy in .xlsx and check the converted file.

PDF is a common way to share a finished report for viewing or printing, but it is not an editable Excel workbook format. Exporting a worksheet or workbook to PDF is appropriate when readers need a fixed presentation rather than the underlying data and calculations.

Templates and Excel add-in files

Template formats create a reusable starting point rather than simply saving a finished workbook. When a user opens an Excel template, Excel normally creates a new workbook based on it, leaving the original template available for future use. Choose .xltx for a template without VBA, or .xltm when the template must include macros. Templates are useful for recurring invoices, monthly reports, or standardized data-entry sheets.

Excel add-ins have their own extensions. The current macro-enabled Excel add-in format is .xlam; .xla is an older add-in format. Add-ins provide reusable features or code that can be made available to Excel, rather than serving as ordinary spreadsheets to edit and share. A user generally enables or installs an add-in through Excel’s add-in controls. Do not rename an add-in to .xlsx: that does not turn it into a standard workbook.

How to choose the right Excel file type

Start with what the recipient must be able to do, then choose the format that retains those capabilities:

For a normal editable spreadsheet: use .xlsx.
For a workbook that must retain VBA macros: use .xlsm, or consider .xlsb if the recipient’s tools support it.
For a reusable starting document: use .xltx or .xltm, depending on whether it needs macros.
For a simple table imported into another system: use .csv, then check delimiters, dates, and identifiers.
For an older program that cannot read modern workbooks: use .xls only if necessary, and check for compatibility warnings or lost features.
For a fixed report that should be viewed or printed: create a PDF rather than treating it as an editable workbook.

When saving in desktop Excel for Windows, use File > Save As, choose the destination, and select a file type from the format list. The precise dialog can vary with the selected storage location. Excel for Mac has a similar Save As workflow, though its dialogs and some controls look different. In Excel for the web, available file operations can differ from the desktop app; download or open the workbook in desktop Excel if a required format is not offered.

Compatibility and feature-loss checks

Excel’s modern formats are designed to retain workbook content, but a format conversion can still change features. When saving to .xls, .csv, or another application’s format, Excel may show a compatibility or feature-loss notice. Read it rather than clicking through automatically. It can identify items that the destination format cannot represent, such as newer worksheet features or workbook elements beyond a CSV’s single-table scope.

Also consider the software on the receiving end. A recent version of Excel generally handles .xlsx and .xlsm, while an old business application may require .xls or a text export. Spreadsheet applications outside Excel may open common formats but render certain formulas, charts, fonts, or conditional formatting differently. For important files, make a separate converted copy and inspect it in the receiving application. Keep the original workbook until the recipient confirms the conversion works.

Common file problems and what they mean

If Excel says a file extension does not match its format, the file may have been renamed incorrectly, saved with a different type, or created by another program. Do not assume that changing report.csv to report.xlsx converts it. Return to the source application and export or save a real workbook in the desired format. If the file came from an unfamiliar source, verify it before opening, especially if it is macro-enabled.

If a file opens with missing formatting or only one sheet, check whether it is actually a CSV or another text export. If formulas appear as values, the file may have been exported to a format that stores data rather than workbook calculations. If Excel warns about compatibility, save a separate copy in the proposed format and compare the important sheets, formulas, charts, and print layout before replacing the original.

Another frequent issue is that an extension is hidden in Windows File Explorer. The filename may appear to end in report even though its real name is report.xlsx. Renaming files without seeing the full extension can accidentally produce names such as report.xlsx.csv. Enable file-name extensions in File Explorer’s View settings to make the full suffix visible.

Security and trustworthy sharing

File formats affect what a workbook can contain, but they are not a complete security check. In particular, .xlsm and .xlsb files can contain VBA macros, and older .xls files can also contain macro code. Only enable macros when the file’s source and purpose are trusted and your organization’s rules permit it. A workbook that does not contain macros can still have other risks, so treat unexpected attachments cautiously.

For routine sharing, use .xlsx when macros are unnecessary, distribute files through approved storage or email channels, and avoid sending sensitive data in a CSV just because it seems simpler. CSV has no workbook-level sheet protection or formatting, and it is easy to expose more rows or columns than intended. Before sharing, check the workbook for hidden sheets, confidential fields, and unintended personal information. A PDF can reduce accidental editing, but it should not be considered a way to secure confidential information by itself.

Frequently Asked Questions

What is the default Excel file extension?
For modern Excel workbooks, the usual default is .xlsx. A workbook that needs to retain VBA macros should instead be saved as .xlsm or another macro-capable format.

Is XLSX better than XLS?
For current work, .xlsx is generally preferable because it supports modern worksheet limits and features. Use .xls when an older system specifically requires the Excel 97–2003 format, and check for features that may be lost.

Can a CSV file contain multiple Excel sheets?
No. A CSV is a plain-text table format and does not store a multi-sheet Excel workbook. Export each needed sheet separately or share an .xlsx workbook to preserve multiple tabs.

Which Excel file types can contain macros?
.xlsm and .xlsb can store VBA macros, and the older .xls format can also contain macros. The .xltm template and .xlam add-in formats support macros as well. Treat macro-capable files from unknown sources with caution.

Does changing a file extension convert the file?
No. Renaming changes the filename, not the internal file format. Open the file in an application that supports it and use Save As or Export to create a genuine copy in another format.

What format should I send to someone who only needs to read a report?
PDF is often suitable when the recipient needs a stable page layout and does not need to edit formulas or data. Send .xlsx instead when they need to inspect or work with the spreadsheet itself.

Try it: the Date Difference Calculator: days, months, years and weekdays between two dates, with the DATEDIF formulas.

More in How-to basics

Sources: Function behaviour and menu paths: Microsoft Support documentation for Excel. Method & sources

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