# How many megapixels is enough for the camera to print A4 photos?

Usually, the photos taken by the smartphone camera are watched on the phone itself. But many users still prefer the familiar traditional paper photographs. To get a high-quality and not grainy photo, it will be enough to print it at a density of 300 dots per inch (DPI, dots per inch). To find out whether a smartphone camera is capable of taking photographs that can be printed in the format of a sheet of photographic paper required by the user, a very simple formula will help. How many megapixels does a smartphone camera need to print quality photos?

How to correctly calculate the megapixel required for a smartphone camera, explained digital photography specialist Ken Rockwell on the pages of his resource. After a certain number, increasing the resolution becomes meaningless, since human eyes are simply unable to distinguish between higher and lower image densities. The need to print photographs on paper is less and less common among users. However, there are even special printers that allow you to print directly from Android devices.

The size of the longest side of the photo (in centimeters) = 10 x [square root of the megapixels of the smartphone camera]

or for those who prefer to count in inches:

Longest side of photo (inches) = 4 x [square root of smartphone camera megapixels]

For example, the resolution of the device's camera sensor is only 4 megapixels. The square root of four is two. The largest photograph taken with this camera that can be printed without loss of sharpness is 15 x 20 centimeters (6 x 8 inches). The 16-megapixel camera allows you to take a high-quality paper photo of 30 x 45 centimeters (12 x 16 inches).

Having made calculations using the Rockwell formula, one can come to the conclusion that, for example, an 8-megapixel camera will print a picture more than twenty-eight centimeters in length. The square root of 8 is 2, 8284.10 x 2, 8284 = 28, 28427 centimeters. In inches - 4 x 2, 8 = 11, 3136. Thus, an 8-megapixel camera can print an 11-inch photograph.

Those users who have 13-megapixel cameras on their smartphones will be able to print photos with a length of 36 centimeters or 14 inches. The square root of 13 is 3.6055.10 x 3.6055 = 36.055, or in inches - 4 x 3.6055 = 14.422.

For comparison, it should be noted that the length of an A4 sheet is 29.7 centimeters, or 11.692 inches, which is only slightly more than the photo size for which an 8-megapixel camera is sufficient, but less than the photo printing capabilities that a 13-megapixel camera can handle. camera phone. There are not many users who will start printing photos taken with a phone over A4 size. Therefore, an 8-megapixel camera is enough for a smartphone in most cases.

The 5-megapixel camera will print quality photos of 10 x 8 inches (25, 4 x 20, 32 centimeters), and the 7-megapixel camera - 14 x 11 inches (35, 56 x 27, 94 centimeters).

Of course, this formula does not include other characteristics of the camera, which are no less, and sometimes even more important, than the resolution of its sensor. Indeed, in fact, the "megapixel" of the camera is not so important.

However, currently there is a tendency to increase the "megapixel" cameras in smartphones. After all, users are pleased to see big numbers, regardless of whether you can get real benefit from them. It is possible that over time, smartphones with 50-megapixel cameras will become commonplace, allowing you to print truly gigantic pictures.

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