Work out megapixel to print size instantly with clear inputs, formula shown and shareable results.
Total pixels are megapixels times a million; splitting them by the aspect ratio gives the pixel dimensions, which divided by the target dpi give the print size in inches. Print size grows only with the square root of megapixels, so doubling resolution buys just 41% more linear print size at the same dpi.
Pixel dimensions
height px = sqrt(total pixels / aspect ratio); width px = height x aspect ratio
Print size
inches = pixels / dpi
height px = sqrt(total pixels / aspect ratio); width px = height x aspect ratio. Total pixels are megapixels times a million; splitting them by the aspect ratio gives the pixel dimensions, which divided by the target dpi give the print size in inches.
Print size grows only with the square root of megapixels, so doubling resolution buys just 41% more linear print size at the same dpi.
Enter camera resolution, aspect ratio, target print resolution. The defaults shown are a realistic worked example — swap in your own figures to get a result you can use.