Before figuring out how big you can print an image, you need to know the pixel dimensions. While there's no single answer, the following is a good range. At 300 PPI, 400x600 pixels can print a 1.3 by 2-inch photo, 1200x1800 pixels can print a 4 by 6-inch photo, and 6,000x9,000 pixels can print a 20 by 30-inch photo.