How Many Megapixels Do You Really Need?
How many megapixels do you really need? The ideal answer is as many as you can get your hands on while retaining image quality, but a more practical answer is to decide based on your final output. The larger your photo needs to be eventually seen, the more megapixels you’ll need.
To get an idea of how large you can print a digital image with good image quality, divide the length and breadth of the image’s resolution by the pixels per inch (PPI) you want to print at – 300ppi is a good quality number, but it is also possible to print photos above or below that number.
For instance, a 10MP image with a resolution of 3872 x 2592 pixels would let you print at a maximum size of 12.9 x 8.64 inches at 300ppi (3872 and 2592 each divided by 300), or approximately A4 size, with good image quality.