Optimal Photo Resolution for Large Format Canvas Printing
In this article, we discuss the optimal photo resolution required to create a high-quality large canvas or archival paper print.
What are pixels and megapixels?
In digital imaging, a pixel is best thought of as the smallest element of detail in which an image is composed. Think of a pixel as a tiny square of color. Each digital photo is made up of millions and millions of these pixels. One megapixel is equivalent to one million pixels (or more precisely, 1,048,576 pixels).
How is photo resolution measured?
The resolution of a digital photo is measured in pixels. The greater the number of pixels per inch (PPI) a digital photo has, the higher quality the photo resolution, and the larger photos you can print.
Not all cameras can capture the same amount of pixels in a photo. How many pixels your camera captures is specified by the quality of the camera sensor - which is measured in megapixels.
Most smartphone cameras today have 10+ megapixel camera sensors. For example, the iPhone X has a 12-megapixel camera. This means the iPhone X generates photos comprised of 12 million pixels. In comparison, entry-level digital cameras have 20+ megapixel cameras. For example, an entry-level Nikon camera has 24 megapixels.
What about digital photo dimensions?
Digital photo dimensions are measured in pixels too (e.g., pixel width x pixel height). For example, a 12-megapixel iPhone X camera generates photos that are 4,288 pixels wide by 2,848 pixels high.
The dimensions of a digital photo are directly related to the camera's megapixel count. Multiplying the pixel width by the pixel height results in total megapixels (e.g., for an iPhone X photo, 4,288 pixels x 2,848 pixels = 12,212,224 pixels = 12 megapixels).
While the photo’s dimensions (e.g., aspect ratio) can change, the total number of pixels in the image are ultimately constrained by the camera’s megapixel count.
How large of a print can I generate given a fixed number of pixels?
Two primary factors determine the size of the print a digital photo can create: 1) the number of pixels in the image; and 2) the printer’s pixel per inch (PPI) specification requirements (sometimes referred to as dots per inch, or DPI).
Most printers recommend a minimum of 150 PPI. This simply means that for every inch of printed space desired, the printer needs 150 pixels of image data.
To find the largest photo quality image you can print, simply divide each pixel dimension of the photo by the required PPI specifications.
For example, a 12-megapixel iPhone X camera with photo dimensions of 4,288 pixels by 2,848 pixels will generate a 28 inch x 19 inch photo (i.e., 4,288 pixels / 150 PPI = 29 inches, and 2,848 pixels / 150 PPI = 19 inches).
Why does PPI matter?
The pixels per inch is ultimately what dictates the quality of the print. Higher PPIs generate higher quality, higher resolution, prints.
Technically, you can print any photo to any size you want, regardless of the number of pixels. But if there are not enough pixels, the quality will be poor when viewed from close proximity (e.g., pixelated or fuzzy).
This of course simplifies the matter. Ultimately other factors such as the subject matter, exposure, focus, and post-processing, all play a role in print quality. But in general, to produce high-quality large canvas and archival paper prints it is recommended that you use a digital camera with at least 24 megapixels.
All else equal, more megapixels equal the ability to print larger, higher quality, higher resolution prints. Most new cameras these days have at least 10 megapixels. This is perfectly fine for generating high-quality prints for smaller dimensions such as 16 inches x 20 inches. But to print in larger sizes, a higher resolution camera is required.
To produce high-quality large canvas and archival paper prints it is recommended that you use a digital camera with at least 24 megapixels. For images at 150 PPI, the table below provides a general guideline for the maximum print size.
 Pixels per inch (PPI) and dots per inch (DPI) are sometimes used interchangeably but are technically different. Both measure picture resolution, but pixels are a digital measurement, while dots are a printing measurement and actually density of dots in image has when printed.