Print Size Calculations

The dimensions of this image are 2025 pixels by 3000 pixels at a resolution of 72 pixels per inch (ppi).

Screen Size in Inches
So the screen size of this image would be:
2025 / 72 = 28.125 inches
3000 / 72 = 41.667 inches
Ans.= 28.125 x 41.667 inches

Print Size in Inches
As print density is 300 dots per inch (dpi), the print size would be:
2025 / 300 = 6.75 inches
3000 / 300 = 10 inches
Ans.= 6.75 x 10 inches

Print Size in Centimetres
Now to find the print size in centimetres, knowing that there are 2.54cm per inch:
6.75 x 2.54 = 17.145cm
10 x 2.54 = 25.4cm
Ans.= 17.145cm x 25.4cm

Print Size in Millimetres
Finally, to find the size in millimetres, we simple multiply by 10, as there are 10 millimetres (mm) in every centimetre (cm). 
17.145cm x 10 = 171.45mm
25.4cm x 10 = 254mm
Ans.= 171.45mm x 254mm