Kiwiguy is correct. Irfanview is great for this and is lightning fast. Just open the photo, click Ctrl+R, a menu opens and you can just select any of a number of sizes, or type in what you want, and save the newly sized image. You can also do 'Batch' resizing - put an entire folder of any size images into it, and it will resize everything to any specified size and put the output into a different folder . You can also convert formats either singly or in batches.