Resizing Photos

On Mac

On Windows using Photos App

1. The Photos app should be the default photo viewer for nearly every image type in Windows.
2. Double-click the image file you want to resize to open it in Photos.
3. Once it's opened, click the three dots in the top-right corner, then click "Resize."
4. A small pop-up will appear, offering you three preset sizes for the picture. Pick one of them, or click "Define custom dimensions" at the bottom.
5. The preset sizes are measured in megapixels.
6. If you picked custom dimensions, a menu will appear that lets you set exactly how big you want the image to be. You can also choose how high quality the resized image will be — higher quality pictures look better, but have a bigger file size.
7. If "Maintain aspect ratio" is checked, then you only need to change either the height or width, and the other dimension will change automatically to match it.
8. Set your new dimensions, and then click "Save resized copy."

On Windows using Microsoft Paint

1. Start Paint, which you can usually find in the Start menu. If it's not there, you can type "Paint" in the Start button search box and click it when it appears in the search results.
2. Open the photo you want to resize by clicking "File," then "Open," and selecting the image from your computer's files. 
3. In the top menu bar's "Home" tab, click "Resize." The "Resize and Skew" window should appear.
4. Enter the size you want to resize the image to. You can set the size by percentage (i.e. "30 percent larger"), or click "Pixels" and enter the exact dimensions you want. As long as you keep "Maintain aspect ratio" checked, you only need to specify the horizontal or vertical dimension, and the other dimension will be set automatically. 
5. Enter the percentage or pixel size to make the new version of your image. 
6. Click "OK" to make the change.
7. Save the new version of your image by clicking "File" and then "Save As."