How to Resize an Image on Windows, Mac and iPhone
You can resize an image without installing anything. Windows has Photos and Paint, a Mac has Preview, and an iPhone has the Shortcuts and Files apps. Each one changes the width and height of the picture.
What the built-in apps can't do is hit an exact file size that an upload form asks for. This guide shows how to resize an image on each device, which method to pick, and what to do when a form sets a size limit.
Quick comparison
| Method | Width and height or % | cm or inches | Exact file size limit | Many images at once |
|---|---|---|---|---|
| Windows Photos | Yes | No | No | No |
| Windows Paint | Yes | No | No | No |
| PowerToys (Windows) | Yes | Yes | No | Yes |
| Preview (Mac) | Yes | Yes | No | Yes |
| Shortcuts app (iPhone) | Yes | No | No | Yes |
| Zelipho online tool (any browser) | Yes | Yes | Yes | Yes |
How to resize an image on Windows 10 and 11
The quickest way to resize an image on Windows is the Photos app. Paint gives you more control, and PowerToys handles a whole folder at once.
With the Photos app
- Right-click the image and choose Open with > Photos.
- Click the See more button (three dots) and choose Resize image.
- Pick a size or type a new width and height, then save a copy.
The options differ between versions of the Photos app: some show a few presets, newer ones let you type the size or a percentage. It works on one image at a time.
With Paint
- Open the image in Paint.
- Choose Resize (or press Ctrl + W) to open the Resize and Skew box.
- Pick Percentage or Pixels, keep Maintain aspect ratio ticked, and enter the new size.
- Use File > Save as so the original stays untouched.
A whole folder at once with PowerToys
Microsoft's free PowerToys adds Resize with Image Resizer to the right-click menu in File Explorer. Select several pictures, right-click, pick a size and they are all done together.
You can set your own sizes in centimetres, inches, percent or pixels, and choose Fit, Fill or Stretch. It is the best option on Windows when you have a batch.
How to resize an image in KB on Windows 10
None of the Windows tools above lets you type a file size. You can only make the picture smaller, check the size in File Explorer, and try again until it is under the limit.
A quicker way is a tool that aims for the limit for you. In our online tool, pick the limit the form gives you; it lowers the JPG quality until the file fits and makes the picture smaller only if it has to.
How to resize an image on Mac
Preview, the app that opens pictures by default, is the easiest way to resize an image on Mac.
- Open the image in Preview.
- Choose Tools > Adjust Size (or click Adjust Size in the Markup toolbar).
- Enter a new width and height, pick a preset from Fit into, or switch the unit to percent.
- Keep Scale proportionally ticked so the picture isn't stretched, then click OK and save.
Preview can also work in inches and centimetres, which is handy for print sizes.
Several pictures at once on a Mac
Open the pictures together in one Preview window and select them all in the sidebar. Then choose Tools > Adjust Size once; the same setting is applied to every picture.
Make the file smaller on a Mac
Apple's tip for a smaller file is to use Adjust Size with Resample image ticked and enter a lower Resolution; the new file size is shown at the bottom of the window. For JPGs, File > Export also has a quality slider.
In Finder, you can also Control-click a photo, choose Quick Actions and then Convert Image (under More if you don't see it) to save a copy in another format and a smaller size.
How to resize an image on iPhone
The Photos app on iPhone can crop a picture but has no resize option. To resize an image on iPhone, use one of two built-in apps.
With the Shortcuts app
- Open Shortcuts and create a new shortcut.
- Add the Resize Image action and set the width, or switch to a percentage.
- Add the Save to Photo Album action after it, so the resized copy is kept.
- Turn on Show in Share Sheet and save the shortcut.
- In Photos, select one or more pictures, tap Share and run your shortcut.
With the Files app
On iOS 16 and later, touch and hold an image in Files, then choose Quick Actions > Convert Image. You pick the format and one of a few preset sizes. You can't type an exact size.
In your browser
Our online tool also works in Safari on iPhone. iPhone photos are often HEIC files; if one won't open, convert it first with the HEIC to JPG converter, which keeps the date the photo was taken.
How to resize image pixels in Photoshop and Lightroom
Photoshop: choose Image > Image Size. Set the width and height in pixels, inches or centimetres, keep the link icon on to keep the proportions, and set Resolution for print. With Resample turned off, Photoshop changes only the print size and keeps every pixel.
Lightroom Classic: resize when you export. In the Export dialog, tick Resize to Fit under Image Sizing and enter the size in pixels, inches or cm. For a size limit, tick Limit File Size To in File Settings and type the value.
Which method should you use?
The right way to resize an image depends on your device and on how many pictures you have:
- One quick photo on Windows: Photos or Paint.
- A folder of photos on Windows: PowerToys.
- Mac: Preview, one picture or many.
- iPhone: a Resize Image shortcut, or Files for a quick smaller copy.
- A form that sets an exact file size: our online tool, on any device.
- Only a smaller file, same width and height: the Image Compressor.
Frequently asked questions
What is the keyboard shortcut to resize a picture in Paint?
Press Ctrl + W. It opens the Resize and Skew box, where you choose percentage or pixels.
How do I keep the shape when I resize an image?
Keep the aspect ratio locked: Maintain aspect ratio in Paint, Scale proportionally in Preview, the link icon in Photoshop. If you need a different shape, crop the picture first.
Do Paint and Photos support centimetres?
No, they use pixels and percent only. On Windows, PowerToys accepts centimetres and inches; on a Mac, Preview does.
Why is there no resize button in the iPhone Photos app?
Photos on iPhone edits a picture's crop, light and colour but not its size. A Shortcuts automation or the Files app's Convert Image action does the resizing.