What’s more annoying than a website rejecting your photo because it’s “too large,” with no hint about what size it actually wants? On most platforms you can resize an image for free without installing anything. Some Android phones are the exception and need a free app for exact pixel sizes. Mac users get the best built-in tool (Preview). Windows users get a solid one (Paint). Phone users get the roughest deal, because the default photo apps mostly crop instead of resizing to exact pixels.
The short answer: use Preview on a Mac, Paint on Windows, the Shortcuts app on iPhone, and your phone’s gallery editor (or a free resize app) on Android. If you need lots of photos done the same way, grab GIMP or use Preview’s multi-image resize. The one big caveat is that resizing changes a photo’s dimensions, and that’s a different job from shrinking its file size.
Quick Reference: Best Way to Resize an Image on Each Platform
| Platform | Built-in Tool | Exact Pixels? | Biggest Catch |
|---|---|---|---|
| Windows 11 | Paint (Resize and skew) | Yes | Photos may offer Resize image too, but Microsoft doesn’t document it |
| macOS | Preview (Adjust Size) | Yes | Save changes the open file; Export makes a copy |
| iPhone/iPad | Shortcuts (resize action) | Yes | You have to build a small shortcut first |
| Android | Samsung Gallery or Google Photos | Samsung: presets (varies by device). Google Photos: crop only | Google Photos crops; it won’t let you type pixels |
| Web | Google Photos editor | No (crop and aspect ratio) | Same crop-only limit as the app |
| Windows/macOS (optional) | GIMP | Yes, plus batch options | Steeper learning curve |
What Does It Mean to Resize an Image?
Resizing an image means changing its pixel width and height. For example, you might shrink a 4000 x 3000 photo down to 1200 x 900 so it fits a profile picture slot or a website upload limit.
Think of pixels as tiles in a mosaic. Resizing removes (or adds) tiles. Compressing keeps the same number of tiles but stores them more efficiently, which shrinks the file without changing its dimensions.
- Resizing: Changes width and height in pixels. Fixes “image must be 1080 pixels wide” errors.
- Compressing: Keeps the dimensions and reduces file size by encoding the image more efficiently. Lossy formats like JPEG discard some detail to do it, while lossless compression (like PNG’s) keeps every pixel intact. File size also depends on the format and its quality settings. Fixes “file too big to email” problems.
- Aspect ratio: The shape of the image (like 4:3 or 16:9). Lock it or your photo gets stretched.
- Who benefits: Anyone uploading to forms, sites, or social profiles, or printing at a specific size.
Shrinking dimensions usually lowers file size too, but if file size is your only goal, our guide on how to reduce an image’s file size covers compression in detail. Working with video instead of photos? That’s a separate job covered in our guide on how to resize a video.
Before You Begin
- A copy of the photo you want to resize (keep the original somewhere safe, like an external SSD or cloud folder)
- The target size in pixels (check the website or form’s upload rules)
- Windows: Windows 11 with Paint and Photos (these typically come preinstalled on most editions)
- Mac: Any current macOS (Preview is built in)
- iPhone/iPad: The Shortcuts app (preinstalled, or free from the App Store if you deleted it)
- Android: Samsung Gallery (on Samsung phones) or Google Photos
- Optional: GIMP, free from gimp.org
How to Resize an Image on Windows
Step 1: Quick Option: Resize in the Photos App
Type Photos in the taskbar search box, open the app, and open your image. The Edit image button (Ctrl+E) gives you crop, rotate, and adjustment tools, according to Microsoft’s Photos editing guide, but resizing isn’t in that panel.
Some versions of Photos also have a Resize image command under the See more (…) menu, with preset sizes and a Define custom dimensions option. Microsoft’s support pages don’t document it, and we can’t promise your version has it, so treat it as a shortcut worth checking rather than an official workflow.
Expected result: If your version has it, you can save a resized copy under a new file name. If it doesn’t, or you want the most control over the aspect ratio, use Paint, the dependable route described below.
Step 2: Open the Image in Paint
For the most control, use Paint. Type Paint in the taskbar search box and open it. Click File > Open, then pick your photo.
Expected result: Your photo appears on the Paint canvas.
Step 3: Open the Resize and Skew Dialog
In the Image group of Paint’s toolbar, click Resize to open the Resize and skew dialog, or press Ctrl+W. Paint’s toolbar layout varies somewhat between versions, so the keyboard shortcut is the quickest route if you can’t spot the button.
Step 4: Enter Your New Size
- Select Pixels instead of Percentage.
- Make sure Maintain aspect ratio is checked.
- Type your new width in the first box. The height fills in by itself.
- Click OK.
Expected result: The image on the canvas gets smaller (or larger). The current pixel size appears in the status bar along the bottom of the window.
Step 5: Save a Copy
Click File > Save as and pick a format like JPEG or PNG. Give it a new name, such as vacation-1200px.jpg, so you don’t overwrite the original.
Expected result: A new resized file sits next to your original.
How to Resize an Image on a Mac
Preview is the best built-in resizer of the bunch. Its Adjust Size dialog includes a Resulting Size readout, so you can see the effect of your new dimensions before you commit.
Step 1: Open the Image in Preview
Double-click the photo in Finder. If it opens in another app, Control-click it and choose Open With > Preview.
Expected result: Your image opens in a Preview window.
Step 2: Open Adjust Size
Click the Show Markup Toolbar button if the toolbar isn’t showing, then click the Adjust Size button. You can also choose Tools > Adjust Size from the menu bar. Both paths are in Apple’s Preview guide.
Step 3: Set the New Dimensions
- Change the unit menu next to Width and Height to pixels.
- Leave Scale proportionally checked so the photo doesn’t get squashed.
- Type a new Width (the Height updates to match), or pick a preset from the Fit into pop-up menu.
- Glance at the Resulting Size readout at the bottom of the dialog.
- Click OK.
Expected result: The image shrinks in the window, and the new pixel dimensions take effect.
Step 4: Save or Export
Choose File > Save to overwrite the original, or File > Export to save a separate copy. I’d use Export every time unless you have a backup. Exporting a separate copy is the safest way to keep the full-size original untouched.
Tip: To resize a batch, open several images in one Preview window, select them all in the sidebar, then choose Tools > Adjust Size. Apple documents this in its Preview resize guide.
Tip: For a quick conversion without opening Preview, select an image in Finder, Control-click it, and choose Quick Actions > Convert Image (in the Finder Preview pane, it’s under More). Choose a format and a size, and macOS saves the converted image for you. Per Apple’s Quick Actions guide, this converts an image to another format or a smaller size. It offers size choices rather than exact pixel fields, so use Adjust Size when a site demands a precise width.
How to Resize an Image on iPhone
The Photos app’s crop tool doesn’t offer a field where you type an exact pixel width and height. One workaround is the Shortcuts app, which includes an action for resizing images in current iOS versions, though the exact name and options can shift between updates.
Setting up a resize shortcut takes about two minutes once, and then it becomes a one-tap tool you can reuse anytime.
Step 1: Create a New Shortcut
Open the Shortcuts app and tap the + button in the top-right corner.
Expected result: A blank shortcut editor opens with a search field for actions.
Step 2: Add the Actions
- Search for Select Photos and tap it to add it.
- Search for Resize Image (or similarly named) and tap it. It drops in below Select Photos.
- Tap the width value inside the resize action and type your target width, like
1200. If the action offers a height option, leave it set to Auto (or equivalent) so proportions are kept. - Search for Save to Photo Album and add it last.
Action names can shift slightly between iOS updates. If a search comes up empty, try just “resize.”
Step 3: Name and Run It
Tap the shortcut name at the top, rename it something like “Resize to 1200,” and tap Done. Tap the shortcut to run it, pick a photo, and let it finish.
Expected result: If the shortcut is set up as described, a resized copy should appear in your Recents album, with the original untouched. We haven’t confirmed the exact action labels and save behavior on every iOS release, so run the shortcut once on a test photo and check the result before you rely on it.
Tip: If you only need a square or a specific shape, the Photos app’s crop tool with aspect ratio presets is faster. Just know that cropping trims the edges and doesn’t set exact pixels.
How to Resize an Image on Android
Android is the messiest platform here because every phone maker ships its own gallery app.
Step 1: Samsung Phones: Use Gallery’s Resize Option
Open Gallery, open your photo, and tap the Edit (pencil) icon. Tap the More (three dots) menu and look for a Resize option, which some versions of Samsung Gallery’s editor include. Pick one of the size options offered, then tap Save or Save as copy.
Samsung doesn’t publish one guide that covers every model, so treat this as a common location rather than a guaranteed one. Availability and the exact menu location vary by phone model and One UI version. If Resize isn’t under More, check the three-dot menu on the main photo view. The catch: on the versions we’ve seen, you choose from preset sizes rather than typing an exact width. If your Gallery has no Resize option, use a resize app from the Play Store.
Step 2: Other Android Phones: Google Photos Crop
Open Google Photos, open a photo, tap Edit, then Crop. Drag the handles or tap the Aspect ratio button to choose a preset like square. Tap Save or Save as copy. These steps are in Google’s editing help page.
Expected result: A cropped photo with the shape you picked. Google’s editing help covers cropping and rotating but doesn’t document a way to type exact pixel dimensions, and features can differ between app versions and accounts. If a site demands precise pixels, use a resize app from the Play Store or send the photo to your computer.
Step 3: On the Web (Any Computer)
Go to photos.google.com, open a photo, click Edit, then Crop & rotate, and drag the edges to crop. Click Save when you’re done. Google notes that some editing features aren’t available on the web, so this is a crop tool rather than a pixel resizer. It’s handy on a borrowed computer with nothing else installed.
Optional: Resize Images Precisely with GIMP
GIMP is free, open-source photo software for Windows and macOS. It’s overkill for one profile picture. It earns its keep when you want exact control or a lot of photos done the same way.
- Download GIMP from gimp.org and install it.
- Open your photo with File > Open.
- Choose Image > Scale Image (this is the menu path in recent GIMP versions; older or newer releases may differ slightly).
- Make sure the chain-link icon next to width and height is linked (that locks the aspect ratio), set the unit to px, and type the new width.
- Click Scale.
- Choose File > Export As, pick a file name and format, and click Export.
GIMP’s plain Save creates a GIMP project file that most websites won’t accept, so Export As is the step you want.
Configuration: Settings That Actually Matter
- Scale proportionally (Preview) / Maintain aspect ratio (Paint) / Chain link (GIMP): Locks width and height together. Leave it on unless you enjoy stretched faces.
- Resample image (Preview): When checked, Preview really adds or removes pixels. When unchecked, it keeps every pixel and changes the print resolution instead. Apple notes that unchecking avoids losing detail. For hitting a pixel target on a website, keep it checked.
- Pixels vs. Percentage (Paint): Use Pixels when a site gives you a number. Percentage is handy for “make it half as big.”
- Aspect ratio presets (Google Photos): Free-form by default. Pick square for profile pics, but remember it crops.
- Storage saver (Google Photos backup): This setting resizes backed-up photos larger than 16MP down to 16MP, per Google’s backup quality help. It’s separate from manual resizing.
Tips and Troubleshooting
Problem: The resized photo looks stretched or squashed
- Undo the resize (
Ctrl+Zon Windows,Command+Zon Mac). - Turn on the aspect-ratio lock in your app.
- Change only the width and let the height follow.
Problem: The file barely got smaller
- Make sure Resample image was checked in Preview. Otherwise the pixel count didn’t change.
- Save as JPEG instead of PNG for photos.
- If it’s still too big, it’s a compression job, so check our guide on reducing an image’s file size.
Problem: Your Android photo got cropped instead of resized
- That’s how Google Photos’ Crop tool works.
- Use Samsung Gallery’s Resize if you have a Samsung phone, a Play Store resize app, or a computer.
Problem: Backed-up photos look smaller than the originals
- Open Google Photos settings and go to Backup > Photos & videos quality.
- Pick a higher-quality option if you want original dimensions kept. It uses more storage.
Problem: You can’t find Resize in the Windows Photos app
- If your version has it, it’s under the See more (…) menu, not in the Edit image panel.
- If you don’t see Resize image, use Paint’s Resize and skew dialog (
Ctrl+W) instead.
Never Enlarge Small Photos: Making a tiny image bigger just makes it blurry. Resizing works best going down.
Printing? If you’re sending photos to a photo printer, check the print shop’s recommended pixel size first. It saves you a reprint.
Wrapping Up
Most devices can resize an image without spending a dime, though some Android phones need a free app from the Play Store for exact pixel sizes. The quality of the experience varies a lot, though. Preview on the Mac is excellent, Paint on Windows is quick once you find the Resize button, and phones make you work harder than they should.
| Step | Action | Applies To |
|---|---|---|
| 1 | Open Paint, click Resize (Ctrl+W), enter pixels, Save as | Windows |
| 2 | Preview > Tools > Adjust Size, then Export | macOS |
| 3 | Build a resize shortcut | iPhone/iPad |
| 4 | Gallery > Edit > More > Resize, or Google Photos Crop | Android |
| 5 | Image > Scale Image, then Export As | GIMP (optional) |
Use GIMP if you resize photos every week or need dozens done identically. Stick with Paint, Preview, or a phone shortcut if you just need one picture to pass an upload form.