Most people assume resizing an image requires professional software. It doesn’t. Both Windows and macOS include a perfectly good built-in option, and there’s also the browser route if you’d rather not open anything at all.
On Windows: using Paint
Paint comes with every copy of Windows and handles basic resizing well.
- Right-click your image, choose Open with, then Paint.
- Click Resize and skew in the toolbar. You can also press Ctrl + W.
- Choose Percentage to scale proportionally, or Pixels to set exact dimensions.
- Keep Maintain aspect ratio ticked unless you need to change the shape on purpose.
- Click OK, then use File > Save as so you don’t overwrite your original.
Always use Save as. Once you’ve shrunk an image and saved over it, you can’t get the original resolution back.
On Mac: using Preview
Preview is the default image viewer on macOS, and it has a resizing tool tucked inside.
- Double-click the image to open it in Preview.
- Go to Tools > Adjust Size.
- Pick your units (pixels, percent, inches or centimeters) and enter the new width or height. With the lock on, the other value updates automatically.
- If you also want a smaller file, you can adjust quality when you export. Use File > Export and move the quality slider for JPG.
Using a browser instead
If you’re on a work computer where you can’t open certain programs, or you’re on a Chromebook, or you simply want the quickest option, a web-based tool works on any device. Upload the picture, type the dimensions or percentage you want, and download the result. Our free online image resizer does exactly that with no software and no account.
Which method should you pick?
- Paint or Preview are fine for one-off jobs on your own computer.
- A browser tool is better when you need to handle several images, switch formats, or work from a phone or a shared computer. See batch resizing explained.
- Design software is worth it only if you also need serious editing.
What size should you enter?
That depends on where the image is going. Some quick guides:
- Email: around 1000 to 1500 pixels wide is plenty. See resizing for email.
- Blog or website: match the width it displays at, then double it for sharp high-density screens.
- Print: work out inches and multiply by 300, as in our DPI vs PPI article.
Things that trip people up
Enlarging. Making an image bigger in Paint or Preview stretches the existing pixels and will look soft. The built-in tools can’t invent detail that isn’t there.
Unticking the aspect ratio lock. Typing in a width and a height that don’t match the original proportions squashes the image. Leave the lock on.
Confusing size with file size. Changing the pixel dimensions usually shrinks the file too, but they’re different things. We explain that in image dimensions vs file size.
On a phone, the process is different, and we cover it in how to resize an image on iPhone and Android.