Choose from many photo sizes, iPhone resolution to wide and HD, including full size image. See it larger for more details:
Different image sizes (resolution): 619 × 700 / 1359 × 1536 / 1811 × 2048 / 100 × 100 / 200 × 200 / 320 × 362 / 619 × 700 / 1415 × 1600 / 150 × 150 / 1830 × 2069
Best you are doing to best and like these to