Megapixels for Digital Photo Printing
How many megapixels (MP) are necessary to produce a high quality digital photo print? Though several factors affect print quality, this page focuses on image resolution, providing answers for questions such as:
If you are not familiar with the term megapixels, you may want to start with our How Many Megapixels Do We Need? article.
Recommended Image Resolution
Before we can answer the question of how many megapixels a digital camera should have, you must decide what print quality is acceptable to you. A digital image is composed of pixels; the denser the pixels, the better it looks on paper. Pixel density is measured as pixels per inch (ppi).
Print sizes up to 8x10"
Common photo print sizes like 4x6", 5x7", and 8x10" are generally viewed at an arms length, requiring a higher resolution image for satisfactory results.
Poster size prints
Prints larger than an 8x10", also called poster size prints, are intended to be viewed from a few feet distance. Because of this, a lower resolution image will produce good results.
Camera Sensor Shape
The shape of the camera sensor, also know as the aspect ratio, has a bearing on megapixel requirements. The sensor is the device behind the lens which records the image; it is synonymous with film in traditional cameras. The two most common sensor shapes are the 2x3 and 3x4.
To determine sensor shape, divide the larger number of the camera's maximum resolution by the smaller—this gives you the aspect ratio. For example, if a camera has a maximum resolution of 2048 x 1536 pixels, the aspect ratio is 2048 ÷ 1536 = 1.33.
Camera Requirements for 150 ppi Prints
To determine how many megapixels a camera should have, select the most common print sizes you intend to create and look up the camera megapixels in the last two columns of the table below.
Note: The megapixel requirements in the table assume that the only cropping performed on the images is to fit the print shape. If you plan on doing significant cropping, increase the camera megapixels accordingly. For example, if half of an image is cropped away, twice as many megapixels are required for the original image. See Cropping Digital Photos Into Shape for details.
Pixel Loss Due to Cropping
You may have noticed that if you multiply the image resolutions in the above table, the results don't always match the camera megapixels. For example, an 8x10" print at 200 ppi has dimensions of 1600 x 2000 pixels. If we multiply the two numbers, the result is 3.2 million pixels. However, the camera requirements are 3.9 and 3.5 MP's. The difference is due to the loss of pixels after cropping the original image into the print shape.
The table below summarizes the percentage of pixels lost for common print sizes.