How to Change File Extensions on Android

How to Change File Extensions on Android Devices

Learn how to change file extensions on your Android phone. Maybe you downloaded a file that has the wrong extension, or you need to rename a file so it opens correctly. Either way, it’s quick to do.

I’ll show you this on a Sony Xperia 1V running Android 15, but the steps work on almost any Android phone from Samsung, Google, OnePlus, and other brands. You just need a file manager app.

What is a file extension and why does it matter?

A file extension is the part after the dot at the end of a file name. It’s usually three or four letters.

Common examples:

• .jpg or .png for images
• .pdf for documents
• .mp4 for videos
• .docx for Word files
• .txt for text files

The extension tells your phone what kind of file it is and which app should open it. If the extension is wrong or missing, your phone won’t know what to do with the file. The file itself is still fine – only the name is the problem. And that’s easy to fix.

What you need

A file manager app. You can use:

• Files by Google (what I use in this guide)
• My Files (Samsung phones come with this)
• Any file manager from the Google Play Store

Most file manager apps work the same way. Pick one you like.

How to change a file extension step by step

Step 1: Open your file manager app
Tap the file manager icon on your home screen or in your app drawer.

Step 2: Navigate to where your file is stored
You need to go to the actual folder location. Skip any “”collections”” or “”categories”” views – these often hide file extensions. Instead:

• Tap “”Internal storage”” or “”Storage””
• Then go to the right folder like Downloads, Documents, DCIM, or wherever your file lives

Step 3: Find the file you want to rename
Look for the file in the folder list. If you see it as a thumbnail, that’s fine. Just make sure you’re in the actual storage folder, not a virtual collection.

Step 4: Long press or tap the three dots
There are two common ways to get the rename option:

• Long press (press and hold) on the file until it gets highlighted, then look for the three dots menu
• Or tap the three dots (?) next to the file name directly

Step 5: Select “”Rename””
A small window will pop up showing the full file name, including the extension.

Step 6: Change only the extension
Here’s the important part. Use your finger to move the cursor. Tap after the dot and change the three or four letters after it.

Example:

• Old name: document.pdf
• To change to a text file: document.txt

Do NOT delete the dot. Just change the letters after it.

Step 7: Save your changes
Tap “”OK”” or “”Rename”” to finish.

What happens when you change an extension?

Changing the extension does NOT change the actual file content. It only changes what your phone THINKS the file is.

Let me explain with an example:

• You have a real PNG image file named “”picture.png””
• You rename it to “”picture.pdf””
• Your phone will now try to open it with a PDF reader
• The PDF reader will fail because the file is still an image, not a real PDF

So changing an extension only works if the file actually IS that format. The extension just tells your phone which app to use.

When should you change a file extension?

Situation 1: The extension is missing
Sometimes files download without any extension at all. For example, a file named “”document”” instead of “”document.pdf””. Adding the correct extension lets your phone open it.

Situation 2: The extension is wrong
Maybe a file downloaded as “”image.txt”” but it’s actually a JPEG. Changing it to “”image.jpg”” fixes the problem.

Situation 3: You accidentally changed it
If you or someone else renamed a file and deleted the extension by mistake, just add it back.

How to fix a file that won’t open after renaming

If you changed an extension and now the file won’t open, don’t worry. The file itself is perfectly fine. You just gave it the wrong label.

To fix it:

1. Go back to the same folder
2. Rename the file again
3. Change the extension back to what it was originally
4. Tap Save

If you don’t remember the original extension, try:

• .jpg or .png for images
• .mp4 for videos
• .pdf for documents
• .txt for text files

Why some apps hide file extensions

Some file managers show “”collections”” or “”categories”” views by default – like “”Images,”” “”Videos,”” “”Documents.”” These are virtual folders that group files from different places. In these views, apps often hide the file extensions to keep things looking clean.

To actually change an extension, you need to go to the real storage location:

• Internal storage
• SD card
• Then into specific folders like Download, DCIM, Documents

Can you change any file extension to anything?

No. Changing “”document.pdf”” to “”document.jpg”” doesn’t turn a PDF into a picture. The file content stays the same. Your phone will just try to open it with the wrong app and fail.

Only change an extension if:

• You know the file actually IS that format
• The extension was accidentally deleted or renamed
• You downloaded a file with the wrong extension but the content is correct

A quick example from the video

In the demonstration, there was a PNG image file. Renaming it to JPEG worked because both are image formats and the image viewer could still read it. But renaming that same image to PDF failed because a PDF reader can’t open an image file.

The file was fine the whole time. Only the name changed.

How to see file extensions on Android

By default, most file managers show the full file name including the extension. If you don’t see extensions:

• Look in your file manager settings
• Find an option like “”Show file extensions”” or “”File name extensions””
• Turn it on

In Files by Google, you see extensions automatically when you’re in internal storage folders.

What about renaming multiple files?

The method above works for one file at a time. Most basic file managers on Android don’t support batch renaming of extensions. If you need to rename many files, you would need a more advanced file manager from the Play Store.

Quick summary

To change a file extension on Android:

1. Open a file manager app
2. Go to Internal storage (not collections view)
3. Navigate to the folder with your file
4. Tap the three dots next to the file
5. Select Rename
6. Change only the letters after the dot
7. Keep the dot (.)
8. Tap Save

Remember: Changing an extension doesn’t change what the file actually is. It only tells your phone which app to try when opening it. If the extension doesn’t match the real file type, the file won’t open correctly. Just rename it back to fix it.