How Many Megabytes Do You Need To Make a Large Print?

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Image file size formula:

width * height * color / 1,024,000 = Megabytes (MB)

  • Values for width and height must be pixels.
  • For color, use the Bytes/pixel number from the table below:
Color Depth Bytes/Pixel
8 bit Grayscale (each pixel = 0 to 255) 1
16 bit Grayscale (each pixel = 0 to 65536) 2
24 bit RGB (8 bits for each R,G,B) "8 bit color" 3
32 bit CMYK (8 bits for each C,Y,M,K) 4
48 bit RGB (16 bits for each R,G,B) "16 bit color" 6

Some Examples:

  • Flatbed scan, 8" x 10" @ 300dpi, 16 bit color
    (8 * 300) * (10 * 300) * 6 / 1024000 = 42 MB (42,187 KB)
  • Flatbed scan, 8" x 10" @ 600dpi, 16 bit color
    (8 * 600) * (10 * 600) * 6 / 1024000 = 169 MB (168,750 KB)
  • Flatbed scan, 4" x 5" @ 1200dpi, 16 bit color
    (4 * 1200) * (5 * 1200) * 6 / 1024000 = 169 MB (168,750 KB)
  • Printed Poster, 24" x 36" x 300dpi, 8 bit color
    (24 * 300) * (36 * 300) * 3 / 1024000 = 227 MB (227,812 KB)