Question: 300 dpi is what resolution?
Answer: A resolution of 300 DPI (dots per inch) gives you the maximum size that you can use for your photo for printing. If you want to use a photo as a background, make sure your photo is at least 21x29. 7cm at 300DPI. If your photos are all at 75 DPI, you should try to calculate their real size at 300 DPI before using them.