Despite the incredible quality of the iPhone camera, some basic editing functions are not included in the stock Photos app. For example, while cropping an iPhone Photo is pretty straightforward, there is no built-in way to resize an image. Emailing a photo may provide the preset options small, medium and large, but what about a custom size?
Luckily there are plenty of options in the App Store when it comes to resizing photos on an iOS device. The six free apps mentioned here mostly provide the basics for a one-time resize or infrequent use. There are also five paid apps listed, which often provide more features and a more polished (and ad-free) user experience. The third-party apps here are just a sampling of similar offerings on iTunes, which reduce the megapixel size of an image.