How to Change a File Extension in Windows 11: A Simple Guide

Changing a file extension in Windows 11 might sound technical, but it’s actually a straightforward process once you know the steps. Whether you want to make a .txt file into a .html file, or convert an image format like .jpg to .png, Windows 11 gives you simple ways to do it. In this guide, we’ll cover what file extensions are, why changing them can be useful, and how you can change them easily without messing up your files.

What is a File Extension?

A file extension is the group of letters after a period at the end of a filename—like .docx, .png, .mp3, or .exe. It tells your computer what type of file it is and which program should open it.

Example: picture.jpg tells Windows it’s an image file.
Another example: report.pdf tells your system it’s a PDF file.

Without the correct extension, files may not open properly, or they might open in the wrong program.

Why Would You Want to Change a File Extension?

You might need to change a file extension for several reasons:

To open a file in another program (e.g., converting .txt to .csv for spreadsheet use).
To fix a mistakenly saved extension (like when a .jpg is saved as .jfif).
To upload files to a platform with format restrictions (some websites only accept .png or .pdf).
For development purposes, such as renaming .html files when coding websites.

Important Warning Before Changing Extensions

Before you start changing file extensions, remember:

Changing the extension doesn’t actually convert the file. For example, renaming a .mp4 video to .mp3 won’t magically turn it into audio—you’ll just make it unreadable.
Some files may become unusable if you use the wrong extension.
Always keep a backup before renaming, especially if it’s an important file.

How to View File Extensions in Windows 11

By default, Windows hides file extensions. So, you first need to make them visible.

Step 1 – Open File Explorer

Press Windows + E or click the folder icon on your taskbar.

Step 2 – Go to the View Options

Click the View tab at the top.
Hover over Show, then select File name extensions.

Step 3 – Verify the Change

Now, you should see extensions like .txt, .jpg, .pdf after file names.

Methods to Change a File Extension in Windows 11

There are a few simple ways to change a file extension.

Method 1 – Using File Explorer

Step 1 – Locate Your File

Find the file you want to rename.

Step 2 – Rename the File

Right-click the file and select Rename.
Or press F2 after selecting the file.

Step 3 – Edit the Extension

Change the text after the period (e.g., from .txt to .html).
Press Enter.

Step 4 – Confirm the Change

Windows will warn: If you change a file name extension, the file might become unusable.
Click Yes if you’re sure.

Method 2 – Using Save As (For Compatible Programs)

Some programs allow you to save a file with a different extension directly.

Open the file in its default program.
Click File > Save As.
Choose the desired format from the list.
Save the file.

This method is safer because it actually converts the file.

Method 3 – Using Command Prompt

If you need to rename multiple files:

Press Windows + S, type cmd, and select Run as administrator.
Navigate to the folder with your files using: cd C:\path\to\your\folder
Rename the file: ren oldfilename.txt newfilename.html

Method 4 – Using Third-Party Tools (For Bulk Changes)

If you need to change extensions for multiple files at once, try tools like:

Bulk Rename Utility
Advanced Renamer

These tools let you rename batches of files in seconds.

When Changing Extensions Works – and When It Doesn’t

Works: .txt → .html (because both are text-based).
Doesn’t work: .jpg → .mp3 (different file types entirely).

If you need real format conversion (e.g., .mp4 to .mp3), use a file converter tool.

Tips for Changing File Extensions Safely

Always make a backup copy before renaming.
Know the file type you want to change to.
Avoid changing extensions of system files or program files (.exe, .dll)—it can break your apps.

How to Revert a Changed File Extension

If you accidentally changed the extension and the file won’t open:

Right-click the file.
Select Rename and restore the original extension.
If you forgot it, check its original file type or open with Open With > Choose another app.

Can You Hide File Extensions Again?

Yes! If you prefer a cleaner look:

Go to File Explorer > View > Show.
Uncheck File name extensions.

Does Changing a File Extension Affect File Size?

No. Renaming a file extension does not alter the actual content or size of the file.

Final Thoughts

Changing a file extension in Windows 11 is easy, but it comes with responsibility. A simple rename can make your files more compatible, fix errors, or help with uploads. But remember—changing an extension does not convert the file format. If you want a true conversion, always use a proper converter or export tool.

FAQs

1. Is changing a file extension the same as converting a file?
No. Renaming only changes the extension, not the file format.

2. Can I change multiple file extensions at once in Windows 11?
Yes, but you’ll need a bulk renaming tool like Bulk Rename Utility.

3. Why can’t I see file extensions in Windows 11?
They’re hidden by default. You need to enable them in File Explorer.

4. Will changing a file extension harm my computer?
Not usually, but it can make files unusable if you use an incompatible extension.

5. Can I change a .exe file to another type?
Technically yes, but it won’t convert it and may break the program.