How to Resize an Image

Resizing an image is a basic computing task that you’re going to need to master at some point. Here’s how to do that regardless of what operating system or computer you’re using.

Resize an Image Using the Web

The easiest way of resizing an image is to use a web app. This should work regardless of whatever platform you’re coming from. Simply upload the image, state your desired dimensions, and let the website resize the image for you.

There is no shortage of services that offer this service free of charge, such as Image Resizer, Adobe Express, ResizeImage, and Piio. These all work in the same basic way: upload, resize, and save your images wherever you want them.

If you’re resizing an image that you would rather stay private, like a note that contains sensitive personal information, you should avoid using these online image resizers. Since the image is uploaded to a remote server, it could be seen by another party (however unlikely this may seem).

In that case, you’re better off resizing the image with local software instead.

How to Resize an Image on Windows

The easiest way to resize an image with Windows is to use the built-in Paint tool. To do this, launch Paint then use File> Open to locate your image. You can also right-click on an image and choose Paint from the “Open with” context menu.

Once your image is open, click on the “Resize and Skew” icon in the “Image” menu at the top of the window. You can now enter a new size in pixels or use a percentage to change its size. Make sure you keep the “Maintain aspect ratio” button in between the two values enabled if you want to keep the current aspect ratio. Failing to do this will warp your image.

Once your image has been resized you can save your changes using File> Save or export it using the File> Save As menu to a format of your choice. Closing the file without saving will discard your changes.

Looking for a faster way of resizing multiple images on Windows? Set up PowerToys Image Resizer to do this from the right-click menu.

How to Resize an Image on a Mac

You can resize an image on a Mac using the Preview tool that’s built into the operating system. First, find the image you want to resize using Finder then double-click on it to open in Preview. You can also right-click and choose Preview from the “Open With” context menu.

Now use the Tools> Adjust Size option to bring up the image resize tool. Enter a new size in pixels or use the drop-down box to change between other metrics like percentage, centimeters, and inches. The aspect ratio will be locked by default as long as the “Scale proportionally” option is checked. Disable this option to unlock the aspect ratio and change vertical and horizontal sizes independently of one another, warping the image.

You can now share your image using File> Save to overwrite, or File> Export to export to another format. Closing the image without saving will discard your changes.

Want a faster way to frequently resize images on your Mac? Build a Quick Action using Automator to do this for you using the right-click context menu instead.

How to Resize an Image on Linux

You can resize an image in Linux using the Terminal and a command line utility called ImageMagick. You can use this utility to do all sorts of things like convert image format, rotate an image, apply effects, and more.

To use ImageMagick, first install it by using your package manager of choice. On Ubuntu, you can do this using the apt-get install command like so:

sudo apt-get install imagemagick

Once the utility has been installed, you can use the following command to resize the image, while maintaining the aspect ratio:

convert image.jpg -resize 1000x500 image.jpg

If you use the same file name, ImageMagick will overwrite the source file. Different file names will create new files. Put an exclamation point after the dimensions to force ImageMagick to ignore the aspect ratio, potentially warping your image. The following command will resize the image to a width of 200:

convert image.jpg -resize 200 image.jpg

To change the height to 200 instead (so that the width conforms to the existing aspect ratio), use this command:

convert image.jpg -resize x200 image.jpg

If you’d rather not work with the command line, consider downloading the free image editor GIMP and using that instead.

How to Resize an Image on iPhone or iPad

You can use Apple’s Shortcuts app to build a workflow for resizing images on iPhone or iPad. The beauty of doing this is that you can use the workflow time and time again, whenever you need it.

Open Shortcuts then tap on the “New Shortcut” plus icon. Click “Add Action” and then add the “Get Images from Input” action. Tap on “Input” and choose “Shortcut Input” to add another step to your workflow. Next, tap on “Nowhere” and make sure that “Show in Share Sheet” is enabled, and hit “Done”.

Now use the search box at the bottom of the screen to find the “Resize Image” action. Tap on “640” and choose “Ask Each Time” so that the workflow prompts you for a size each time you run it.

Finally, use the search box to find the “Quick Look” action. This will display the resulting image in a preview window, giving you the option of saving it, sharing it, or dismissing it. You could also add an action like “Save File” or “Save to Photo Album” if you’d rather save the file instead of previewing it.

Give your Shortcut a name and an icon then save it. You can now locate an image you want to resize, hit “Share” then tap “Edit Actions” and add your newly created shortcut to the list of actions that appear on the share sheet. In the future, you can simply hit Share and then run your workflow.

If you’d rather just use a third-party app to do this you can download Image Size for free and use that instead.

How to Resize an Image on Android

Resizing an image on Android requires the use of a third-party app, of which there are plenty to choose from. Image Size is one of the highest-rated such apps, and it gets our iPhone recommendation too.

Download the app from Google Play and open it, then tap on the “Image” icon at the top of the screen and import the image you want to resize. Use the “Pixel” section to specify a pixel size that you want to use. By default, the app will maintain the aspect ratio, but you can tap on the “link” icon between the height and width values to change this.

Once you’ve resized your image, hit the “Save” button at the bottom of the screen to save your image. Other apps you might want to try include Pixlr and Resize Me!.

Web Apps Are Ideal for Most Users

If all you need to do is resize a profile image or throwaway photo, using a website to upload and resize your image is just fine. For more sensitive photos or document scans, make sure you use a local native app instead.

A smaller file size is one reason you might want to resize an image. Learn how to compress PDFs to make them smaller too.