How to resize an image on iPhone (and make it smaller in MB)

How to resize an image on iPhone: the short answer

Photos crops; Preview resizes. The Photos app has no width and height box: it cuts a part of the picture away. For exact pixels, or a smaller file in MB, open the photo in Preview, the app Apple added to iPhone in iOS 26. On an older iPhone, a web tool in Safari does both. Here is every route, and what Apple itself says about it, read on iOS 27:

Crop a photo in Photos, and keep the original

1. 1

   Open the photo and tap Edit

   Then tap the Crop button.

2. 2

   Drag the corners, or pick a shape

   The frame keeps the photo’s shape until you tap the lock in the top-right corner. Apple names Square, Wallpaper, 9:16 and 5:7 among the presets.

3. 3

   Tap Done

   The crop is saved on the same photo. To undo it later, tap More, then Revert to Original.

A crop does not make a new file. Photos saves it as an edit on the same photo, and Apple’s crop page says you can still revert to the original after you save. To keep the whole photo and a cropped copy, tap More, then Duplicate first, and crop the copy.

Does a crop make the file smaller?

The copy you send, yes, because it holds fewer pixels. Apple does not say by how much, and the guides argue both ways, so we measured it. A square cut from the middle of our 4964 × 2782 photo keeps 56% of the pixels and saved at 366.8 KB, against 605.5 KB for the whole photo, both through our engine at Auto. The library itself does not shrink, because the original stays for Revert.

Resize and compress in Preview (iOS 26 and later)

Preview is the iPhone’s own way to set exact pixels and a smaller file. Apple’s pages start from an image already open in Preview; MacMost’s walkthrough sends one from Photos with Share, then Preview. Preview opens files from the Files app too.

Adjust photo size on iPhone: More, Adjust Size

1. 1

   Tap More, then Adjust Size

   Apple’s Preview editing page says to choose options, then tap Done. Apple does not list the options; MacMost and CleverFiles show pixels, percent and inches, with the sides kept in proportion.

2. 2

   Type the new width

   Instagram sizes a wider feed photo down to 1080, as our Instagram size guide shows, and Apple’s older Shared Albums kept 2048 on the long edge, so either is plenty for a screen. The chart below shows what each width weighs.

3. 3

   Tap Done

   To undo it, tap More, then Undo.

Reduce photo file size on iPhone: Export and the Size slider

1. 1

   Tap the menu next to the file name, then Export

   Pick a format: HEIC, JPEG, PDF, PNG or TIFF.

2. 2

   Move the Size slider

   For HEIC and JPEG, Apple’s export page says to drag it left for a smaller file, right for higher quality.

3. 3

   Choose where to save it, then Save

   The export is a new file; the photo you opened stays as it was.

How much smaller each size makes the file

Almost no ranking guide measures anything, so we did. Our sample is a 9.8 MB JPEG, 4964 × 2782, saved at a very high quality. Every row below is our engine at Auto:

Two things stand out. From the 9.8 MB original, quality does most of the work: our engine took the photo to 605.5 KB at full size, no resize at all, and to 370.2 KB at quality 60, all 4964 × 2782 pixels kept. A 1 MB limit needs no resize either: under a 1 MB cap our engine kept all 4964 × 2782 pixels at 996.5 KB, and 497.7 KB under 500 KB. Pixels do the rest: at 1080 wide the photo keeps 4.7% of its pixels and weighs 56.7 KB; at 2048 wide, 155.1 KB.

Does resizing lose quality you can see?

Only when you zoom in. On a phone screen a 1600-wide copy looks the same as the original; enlarged, the fine detail is gone, and no app can put it back:

Make a one-tap resize shortcut

For many photos, a shortcut is faster than Preview. Apple’s Shortcuts guide gives “resizing an image” as its example of an action that transforms content, though it does not document the action’s options. In the Shortcuts app, make a new shortcut that receives images from the share sheet, add Resize Image with the width you want, then Save to Photo Album. From then on, select photos in Photos, tap Share and run it. The originals stay as they were.

Compress images on iPhone without an app

On an iPhone older than iOS 26, or for a size limit Preview cannot promise, use a web tool in Safari. The image resizer sets exact pixels; the tools to compress an image to 1 MB or reduce image size in MB to any cap land at or under the number, which Preview’s slider does not. Tap the upload area, choose Photo Library, pick the photos and save the results to Files or Photos.

Files Convert Image and Mail sizes: what Apple does not say

Most videos on this topic show a Convert Image quick action in the Files app, with a format and a size. Apple documents Convert Image only for the Mac’s Finder, in its Mac User Guide; its iPhone guide does not describe it, and no page gives what its sizes are in pixels.

The old email trick is the same story. Mail on a Mac has an image size menu. Apple’s iPhone Mail guide, checked for iOS 12, 15 and 27, describes no size choice when you attach a photo. A file too large for your mail account goes by Mail Drop, which takes attachments up to 5 GB. Preview, above, gives you the same result with sizes you choose.

When to convert HEIC to JPEG, and what it does to the size

Convert only when a website or a person needs JPEG. Apple’s HEIF page says HEIF compresses better than JPEG at the same visual quality, so the camera’s Most Compatible setting, which saves JPEG, makes bigger files than High Efficiency. A conversion at Auto can still come out smaller: our engine turned a real iPhone 12 Pro HEIC of 1,956.0 KB into a 940.7 KB JPEG. When you share, tap Options in the share sheet: Automatic picks a format for the destination, Current sends the file as it is, and Most Compatible may convert it to JPEG. For a batch on any computer, use HEIC to JPG.

What Messages, AirDrop and iCloud do to photo size

• Messages may compress photo attachments when necessary, Apple says. To send smaller ones on purpose, turn on Send Low Quality Photo Previews in Settings, Apps, Messages (older pages call it Low Quality Image Mode).
• AirDrop with Current in the share sheet’s Options sends the photo with no format conversion; All Photos Data sends the original file with its edit history.
• Shared Albums made on iOS 26 or earlier reduce photos to 2048 pixels on the long edge. Albums made on iOS 27 keep full resolution, so the old trick of saving a copy from a shared album no longer shrinks anything.
• Optimize iPhone Storage keeps storage-saving versions on the phone and the originals in iCloud. It frees space; it does not give you a smaller file to send.

How to check a photo’s size in MB

Open the photo in Photos and swipe up, or tap the Info button: the panel lists the file size, which Apple documents from iOS 15. Check it before and after, so you know the method worked.

Take smaller photos from now on

In Settings, Camera, Formats, High Efficiency saves HEIF, and Photo Mode picks 12 MP instead of the 24 MP default on supported models. Leave ProRAW off unless you edit raw files: Apple puts a ProRAW photo at about 25 MB at 12 MP and 75 MB at 48 MP, 10 to 12 times a HEIF or JPEG. Our guide on how to reduce image file size covers the same settings on Android, Mac and Windows.