To compress a JPEG on iPhone, use tools already on your phone: the Mail app's size picker, a resizing recipe in the Shortcuts app, or the camera's High Efficiency format. These reduce photo size when emailing or uploading, with no extra software. Small, Medium, and Large options in Mail handle quick sends. A reusable Shortcuts workflow handles batch jobs. An online compressor in Safari covers one-off files.

Use the IPhone Mail App to Shrink Photos

Attach large photos in the iPhone Mail app and it offers to reduce the message size with Small, Medium, Large, and Actual Size. You stay in the email screen. Here is how:

  1. Open the Mail app and start composing a new message.
  2. Tap the attachment icon and select photos from your library.
  3. After attaching, look for a prompt asking if you want to shrink the message size. Choose Small for the smallest file size, Medium for a balance, or Large for higher quality.
  4. If no prompt appears, the photos may already be small enough. Cancel and try a different method.

Mail Drop sends attachments up to 5 GB as a download link instead of shrinking them. That suits very large files, but it does not compress the photos themselves. For most email attachments, Small, Medium, or Large works well.

Build a Shortcuts Recipe to Resize Images

The Shortcuts app has a Resize Image action that scales photos to a chosen width, reducing file size. Combine Select Photos, Resize Image, and Save to Photo Album to make a reusable compression workflow. Nothing to install.

Create the Workflow

  1. Open the Shortcuts app and tap the plus sign to create a new shortcut.
  2. Add the "Select Photos" action. This lets you pick images from your library when you run it.
  3. Add the "Resize Image" action. Set the width you want. The height adjusts automatically to keep the aspect ratio.
  4. Add the "Save to Photo Album" action. Choose an album name, like "Resized."
  5. Name the shortcut, such as "Compress Photo."

Run It

  1. Open the Shortcuts app and tap your "Compress Photo" shortcut.
  2. Select one or more photos from your library.
  3. The workflow resizes them and saves the smaller versions to the album you chose.

Reducing pixel dimensions cuts file size roughly in proportion to the number of pixels removed. A photo resized to half its width and height becomes about one-quarter of the original file size. This works for JPEG, PNG, and WebP images.

Set the Camera to High Efficiency Format

Settings > Camera > Formats > High Efficiency stores new photos as HEIC, which is smaller than JPEG but less widely accepted. Set this before you shoot to save storage and upload time.

Go to Settings > Camera > Formats and select High Efficiency. New photos save as HEIC instead of JPEG. Some websites and apps will not open HEIC files directly. Convert them later if needed.

Use an Online Compressor in Safari

An online compressor in Safari works on photos selected from your library. This is the quick option when you do not want to build a workflow or change camera settings. Open Safari, go to a compression site like compressjpeg.onl, and upload your photo from the library. The site shrinks the image and you download the smaller version. No app installation needed. It runs entirely on your iPhone.

Compare the Methods for Different Needs

Each method has its best use case:

  • Mail app size picker: Best when you are already composing an email and need to shrink photos on the fly. Options are Small, Medium, Large, and Actual Size.
  • Shortcuts resize workflow: Best for batch resizing or a reusable tool. You control the exact width.
  • High Efficiency camera format: Best for new photos you plan to keep in HEIC. Saves storage but may not work everywhere.
  • Online compressor in Safari: Best for one-off compression of photos already on your phone. No setup required.