Pixel to Inch Ratio

Standard pixel to inch ratio is supposed to be 96 pixels. Using 3.81 pixels per millimeter and converting that to an inch. I know that most photo printers would tell you it is 300dpi is the standard. That is where it can get confusing, if you don't know mathematics. You can figure pixels per inch by using the Pythagorean Theorem. More information about pixels per inch and math can be found here .