How Many Megapixels Do We Need?

The major camera manufacturers are in a megapixel race. They are telling us that we need more and more pixels. But what for? If we are just publishing our pictures on the Internet we need fewer pixels, usually with files sizes less than one megapixel. If we intend to make prints what do we need? The following chart is from Fotomoto, a major online print selling service for photographers. Notice that all the file sizes up to 30×45 inch prints are smaller than the typical DSLR files today.
Suggested Resolution for Prints
Print Size ORIGINAL PHOTO MUST BE
Small (like 6″x8″, 6″x9″, 6″x12″, etc): At least 1080×1080 (around 1.1 Megapixels)
Small to medium (like 8″x10″, 8″x12″, etc): At least 1440×1440 (around 2.0 Megapixels)
Medium (like 9″x12″, 10″x15″, etc): At least 1800×1800 (around 3.1 Megapixels)
Medium to large (like 12″x16″, 12″x18″, etc): At least 2160×2160 (around 4.4 Megapixels)
Large (like 16″x20″, 18″x24″, 16″x24″, etc): At least 2880×2880 (around 7.9 Megapixels)
Very Large (like 20″x20″, 20″x25″, etc): At least 3600×3600 (around 12.4 Megapixels)
Extra Large (like 24″x30″, 24″x36″, etc): At least 4320×4320 (around 17.8 Megapixels)
XX Large (like 30″x40″, 30″x45″, etc): At least 5400×5400 (around 27.8 Megapixels)

My 24 megapixel cameras produce files at 4000 x 6000 with a total file size of 68.7 Megapixels. Do you want to publish a magazine cover? Five Megapixels will do. My stock agency tells me they rarely send out a file any larger than 12 Megapixels. Are you thinking of upgrading from a 16M camera to get more Megapixels? You probably do not need to unless you are after some features other than Megapixels. The micro 4/3rd cameras produce a file size of 4608 x 3456 with a file size of 45.6 Megapixels. According to the above chart that is enough for prints 24 x 36 inches. That from a sensor half the size of so-called full frame camera. I keep a little Sony RX100 with me all of the time. Its one-inch sensor produces file sizes of 57.1 Megapixels. Of course there are other considerations besides file sizes. Color depth and dynamic range are generally better with larger sensors. So let each person choose according to budget and needs. For most photographers we have reached already files sizes sufficient for most any purpose.

Taken with the Sony RX100 at a farmers’ market in eastern Tennessee.