Whats a megapixel, and how many do I need?
A megapixel is equal one million pixels, or distinct color dots. A 2.2 megapixel camera, for instance, captures digital images with 2.2 million pixels of color. The larger the final, printed digital image, the more likely these distinct color dots will begin to show. What this means is that you should choose the megapixel rating of your digital camera based on the size of the prints you’d like to create. The more pixels you have, the larger your pictures can be printed, says Dave Johnson, author of How to Do Everything with Your Digital Camera.
