Reduce Photo Size on iPhone or Android Without an App
Short answer
Crop first — it removes pixels without degrading what remains. On iPhone, save the photo to Files, long-press it and choose Quick Actions → Convert Image, then pick Small for roughly 100–250KB. On Android, use your manufacturer's gallery Resize image option, or drop the camera's picture size to 12MP.
On this page
You are trying to attach a photo to a form on your phone, the site says the file is too large, and the App Store is full of “photo resizer” apps that want a subscription to do thirty seconds of work.
Both iPhone and Android can do it with what is already installed. The methods are not advertised, which is the only reason those apps exist.
Crop first — it works everywhere
Before anything else, crop. It is available on every phone, it takes seconds, and it is the only method that costs you nothing in the region you keep.
File size tracks pixel count. Cropping away half the width and half the height removes 75% of the pixels, and the part that remains is bit-for-bit as detailed as it was. Compression, by contrast, degrades the whole image.
- iPhone: open the photo → Edit → the crop icon (bottom right) → drag the corners → Done. Tap Duplicate first if you want to keep the original, since iPhone edits are applied to the photo itself.
- Android: open in Google Photos → Edit → Crop → drag → Save copy.
For a screenshot of an error message, cropping to just the message often takes the file from 2MB to 150KB on its own.
iPhone: the Files app conversion
This is the hidden one, and it is the most useful. It has been in iOS since 16.
- In Photos, select the photo and tap the share icon.
- Choose Save to Files and pick a folder (On My iPhone → Downloads is fine).
- Open the Files app and navigate to it.
- Long-press the file → Quick Actions → Convert Image.
- Choose JPEG or PNG, then pick Small, Medium, Actual Size, and whether to keep metadata.
Rough results from a typical 12-megapixel phone photo:
| Option | Approximate output |
|---|---|
| Small | 100–250KB |
| Medium | 400–800KB |
| Actual Size | Unchanged dimensions, format converted only |
This is also the easiest way to turn a HEIC into a JPG on the phone itself, since the conversion dialog lets you pick JPEG regardless of the source format. Choosing Remove Location at the same time is worth doing for anything you are uploading to a form.
You can select several files first and convert them in one go.
iPhone: the Mail resize prompt
An older trick that still works and needs no file management.
- Select the photos in Photos → share → Mail.
- Address the message to yourself.
- Tap send. Mail shows a prompt: Small, Medium, Large, Actual Size.
- Open the received email and save the resized images back to Photos.
| Mail option | Long edge | Typical size |
|---|---|---|
| Small | ~320px | 20–50KB |
| Medium | ~640px | 60–150KB |
| Large | ~1280px | 200–500KB |
| Actual Size | Original | 2–5MB |
It is clunky, and it only appears when the attachment is large enough to be worth resizing, but it requires nothing but Mail.
iPhone: stop making huge files in the first place
If the problem is recurring, change what the camera captures.
Settings → Camera → Formats → High Efficiency keeps photos as HEIC, which is roughly half the size of the JPG equivalent at the same quality. If you chose Most Compatible at some point to make photos work on a Windows PC, you doubled every file size — see converting HEIC to JPG for better ways to handle that.
Settings → Camera → Formats → Photo Mode on recent iPhones lets you choose 12MP instead of 24MP or 48MP. For anything that will be viewed on a screen or uploaded to a form, 12MP is already more than enough, and it halves or quarters every file.
Settings → Camera → Preserve Settings stops the camera reverting to a larger mode each time you open it.
Android: look in the manufacturer’s gallery
Google Photos has no resize export — deliberately, because its model is to keep originals in the cloud. Your phone’s own gallery app usually does.
Samsung Gallery: open the photo → three-dot menu → there is frequently a Resize image entry offering percentages or preset dimensions. Some firmware versions place it under Details instead.
Other manufacturers: check the share sheet. Several Android skins intercept sharing and offer “Reduce image size before sending” as an option when the target app is email or a messaging service.
Via the share sheet to Gmail: attaching a large photo to a Gmail draft sometimes triggers a resize offer, in the same spirit as iOS Mail. It is less consistent than on iPhone.
Android camera settings
Camera app → Settings → Picture size / Aspect ratio. Dropping from 50MP or 108MP to 12MP is the single biggest change available, and on a phone screen you will not notice. High-megapixel modes on Android phones mostly exist for marketing; the sensor bins pixels together anyway in normal lighting.
Some Androids also offer HEIF as a capture format under the same menu, which roughly halves file sizes compared to JPG.
The screenshot trick, and why it is a last resort
Open the photo full-screen, take a screenshot, use the screenshot.
It does shrink things, because the screenshot is at screen resolution — around 1170 × 2532 on a modern iPhone — rather than camera resolution. But:
- You capture the whole screen, including status bar and any interface, so you have to crop anyway.
- The photo is displayed fit-to-screen, so you lose the edges or gain black bars.
- You have no control over quality, and the result is a re-compressed copy of an already-compressed image.
- On iPhone, screenshots save as PNG, which for a photograph is often larger than the JPG you started with. This surprises people regularly.
Use it when nothing else is available and the photo is a diagram or a receipt where fidelity does not matter.
The browser route
Worth knowing: your phone’s browser is a capable image tool, and a browser-based compressor runs on the phone rather than on a server.
Our image compressor works on mobile. Open it in Safari or Chrome, tap to select photos from your camera roll, set a maximum dimension and a quality level, and download the results back to Photos. Because the processing happens on the device, nothing is uploaded — which matters for documents and ID photos, and for any photo carrying GPS coordinates.
It gives you something no built-in option does: a visible before-and-after size, so you can target a specific limit rather than guessing between “Small” and “Medium”.
What not to do
- Do not install a free resizer app that wants photo library access. Many monetise by uploading your library. The built-in options cover the same need.
- Do not send the photo through WhatsApp to shrink it. It works — WhatsApp downscales to roughly 1600px — but you also get heavy recompression, stripped metadata and no control over the result.
- Do not edit the original without duplicating. iPhone edits are non-destructive and revertible, but a photo saved out at Small from Files is a new, permanently smaller file.
- Do not expect camera settings to fix existing photos. They only affect new captures.
- Do not zoom in and screenshot to “crop”. Crop properly; it is lossless for what remains.
What to expect
Cropping plus the Files app conversion on iPhone, or a gallery resize on Android, handles essentially every upload limit you will meet on a phone. A 4MB photo becomes 150–300KB in under a minute without installing anything.
If you need to hit a precise kilobyte target rather than just “smaller”, that needs a tool with a quality slider — the method is in compressing a photo to an exact size.