How to reduce photo size on iPhone, and resize photos for email

Contents7 sections

1. Why are iPhone photos so big?
2. How do I make new photos smaller?
3. How do I reduce the size of a photo I’ve already taken?
4. How do I resize a photo to send by email?
5. Is there an app that compresses photos in bulk?
6. Will reducing photo size lose quality?
7. Questions people ask

For new photos, set Settings > Camera > Formats to High Efficiency and choose 12 MP under Photo Mode. For a photo you've already taken, save it to Files, open it in the Preview app, tap Export and drag the Size slider left. Cropping in Photos doesn't save space, because Photos keeps the original so you can revert.

Why are iPhone photos so big?

Because recent iPhones take bigger photos by default. On the iPhone 15, 16 and 17 families, including the iPhone Air and 16e, the main camera saves at 24 MP unless you change it. Apple’s camera guide explains how to drop it to 12 MP or turn on 48 MP.

The format matters as much as the pixels. Apple’s HEIF and HEVC page says High Efficiency photos use less storage than JPEG while preserving the same visual quality.

Then there’s ProRAW. On Pro models it gives editors the most to work with, and it costs space for it. Apple’s ProRAW page puts a ProRAW photo at about 25 MB at 12 MP and about 75 MB at 48 MP, and says ProRAW files are 10 to 12 times larger than HEIF or JPEG.

How do I make new photos smaller?

Two settings do most of the work, and both only affect photos you take from now on.

1. Open Settings > Camera > Formats and choose High Efficiency.
2. Tap Photo Mode and choose 12 MP instead of 24 MP.
3. If you don’t edit RAW files, leave ProRAW & Resolution Control (or Resolution Control, depending on your model) turned off.

Setting	Where	What it changes
High Efficiency	Settings > Camera > Formats	HEIF instead of JPEG: smaller, same look, per Apple
Photo Mode: 12 MP	Settings > Camera > Formats > Photo Mode	Fewer pixels than the 24 MP default
ProRAW off	Settings > Camera > Formats	Avoids files of about 25 to 75 MB each

How do I reduce the size of a photo I’ve already taken?

Use Preview, Apple’s app for PDFs and images, on iOS 26 and later. It works on files, so the photo goes to Files first.

1. In Photos, open the photo, tap Share, then Save to Files.
2. Open Preview and open the photo from where you saved it.
3. Tap More (the three dots) next to the file name, then Export.
4. Choose JPEG or HEIC, then drag the Size slider left for a smaller file.
5. Choose where to save it, rename it if you like, and tap Save.

Apple’s Preview export guide describes the slider simply: left for a smaller file, right for higher quality. Check the result before you delete the original. You can’t get the detail back.

What doesn’t work is cropping in Photos. It changes what you see, but Photos keeps the original so that Revert can undo the edit. The space stays taken.

How do I resize a photo to send by email?

Start with Mail itself. Apple says that if an attachment is over your email account’s limit, Mail can send it with Mail Drop instead.

For a smaller file the other person can open anywhere, export a JPEG from Preview with the Size slider turned down, as above, and attach that. If you only need it to open on a PC, the share sheet helps too: in Photos, tap Share, then Options, and choose Most Compatible. Apple says files may then convert to JPEG. That’s about compatibility, not size, so it won’t always be smaller. Our guide to converting HEIC to JPG covers that in more detail.

For Messages there’s a setting. Go to Settings > Apps > Messages and turn on Send Photo Previews or Low-Quality Image Mode, whichever your iPhone shows. Apple’s Messages help suggests it when full-size photos won’t send.

Is there an app that compresses photos in bulk?

Yes. Preview handles one photo at a time, which is fine for an email and slow for a holiday. Siftlo, a phone app that sorts, deduplicates and clears photos and files, has two tools for the rest.

Compress (“Smaller, same look”) re-saves photos at a smaller file size. Resize (“Set a maximum size”) caps the long edge, for when a website or form asks for photos no wider than a set size. Both work on HEIC, JPEG, PNG and WebP, and both show you the before and after first.

You choose whether to save the smaller photos as new copies or replace the originals. If you replace them, your iPhone asks you to confirm and the originals go to Recently Deleted, so Siftlo says queued to free until that album is emptied. The work runs on the phone; nothing is uploaded.

On Free, Compress, Resize and Convert share 100 photos a month. Siftlo Plus has no limit.

Will reducing photo size lose quality?

Some, and how much depends on how far you go. A lower Size setting or a smaller maximum size throws away detail you can’t get back, so keep the originals of anything you might print or crop later.

If space is the real problem rather than file size, there’s a gentler option. With iCloud Photos and Optimise iPhone Storage on, Apple’s iCloud Photos guide says full-resolution photos stay in iCloud while space-saving copies are kept on the phone. Nothing is lost, as long as you keep enough iCloud storage.

Videos usually take far more room than photos. Our guide to compressing a video on iPhone covers those, and how to free up space on iPhone covers the rest of a full phone.

Questions people ask

Is HEIC smaller than JPEG?

Yes. Apple says HEIF and HEVC compress better than JPEG and H.264, so they use less storage while preserving the same visual quality. When you share a HEIC photo, your iPhone may send it as a JPEG automatically so the other person can open it.

Does Optimise iPhone Storage make my photos smaller?

Only the copies on your phone. With iCloud Photos and Optimise iPhone Storage on, Apple keeps the full-resolution photos in iCloud and stores space-saving copies on the device when needed. Your originals aren't touched.

Do photos lose quality when I send them in Messages?

They can. Apple says the iPhone can compress photo and video attachments when necessary. Apple also suggests turning on Low-Quality Image Mode if full-size photos won't send.