Resizing photos before posting them to Facebook can make your pictures easier to work with, helping you to avoid long load times or having to crop large chunks out of an image. In addition, Facebook sets a minimum size requirement on profile images, requiring them to be at least 180 pixels wide in order for the system to accept them. Both the Windows and Mac OS X operating systems feature built-in tools that allow you to resize images without skewing the picture's aspect ratio, letting you modify your pictures for Facebook use without having to install third-party software.

On Windows

Step 1

Open the Charms bar, click on the Search charm and type “paint” (without quotes).

Step 2

Click on “Apps” and then click on “Paint” to open the Paint program.

Step 3

Click “File” and select “Open” from the drop-down menu. Select the picture you wish to resize and then click the “Open” button to open it in Paint.

Step 4

Click the “Home” tab and select “Resize” to open up the Resize And Skew dialog box.

Step 5

Check the “Maintain Aspect Ratio” box. This ensures that the image will retain its height-to-width ratio once resized.

Step 6

Select either “Percentage” or “Pixels” from the Resize menu. “Percentage” allows you to set the image to a percentage value of its original size, while “Pixels” allows you to set a specific value for the image's height or width. If you selected “Percentage,” enter a percentage value into either the “Horizontal” or “Vertical” boxes. If you selected “Pixels,” enter either a new height for the image into the “Vertical” box or a new width for the image into the “Horizontal” box. Click “OK” to confirm your changes.

Step 7

Click “File” and then “Save” to save your changes to the image.

On Mac OS X

Step 1

Open the Finder and browse to the image you want to resize. Double-click on the file to open it in Preview.

Step 2

Click “Tools” and then select “Adjust Size” from the drop-down menu to bring up the Adjust Size dialog box.

Step 3

Check the “Scale Proportionally” box. This ensures that the image will retain its height-to-width ratio once resized.

Step 4

Enter either a new height for the image into the “Height” box or a new width into the “Width” box. Click “OK” to confirm your changes.

Step 5

Click “File” and then “Save” to save your changes to the image.