On device image resizing for Android

Android natively does not offer an easy way to batch edit photos and resize them in bulk. However there are several apps on the play store which do this well.  

Recommended method: 

Visit the play store on your device and install the photo and picture resizer app.

It can be downloaded from the play store here: 

https://play.google.com/store/apps/details?id=com.simplemobilephotoresizer&hl=en_US

Step-by-Step Guide:

1. Open Your Gallery: Go to your phone's default gallery app (like Google Photos or Samsung Gallery).
2. Select Multiple Photos: Tap and hold one image to select it, then select all the other photos you want to resize in bulk.
3. Initiate Sharing: Tap the Share icon (often a sideways '<' or three connected dots).
   Choose the Resizer App: From the list of apps, select "Photo & Picture Resizer" (or "Resize").
4. Select Resize Option: The app will open with your selected images; choose your desired size, either a preset percentage (like 50%, 75%) or custom dimensions (width/height in pixels).
5. Resize & Save: Tap the resize button (often a play/start icon).
6. Find Your Resized Photos: The app creates a new folder in your gallery containing all the resized images. You can then share them directly from the app or gallery.