When you upload a profile picture to Facebook, the image is resized if it's too big. However, what most people don't know is that while your profile picture is only allowed to be 180 pixels wide, it can be 540 pixels tall. This means that you can create a full size photo for your Facebook profile --- as long as you crop it so that it fits within Facebook's required dimensions.
Launch your photo editing program and open the photo you want to use as your profile picture.
Crop your photo to make it 540 pixels tall by 180 pixels wide. Save your photo after you are finished.
Launch Facebook and log into your account.
Click on your profile picture, and click "Change Picture."
Click "Choose File" and select the image you just cropped. When you are finished uploading your photo, the full-sized picture will be displayed in your Facebook profile.
If your Facebook profile photo is even 1 pixel larger than the allowed width or height, it will be resized.