Measuring 40x60cm, 16x24" is a common size for photo prints, art work and posters. The standard way to measure a print is by measuring width by height.
To get the best print result for 16x24", you'll need at least 1152 x 1728px and ideally 4800 x 7200px.
If you are looking for a frame with a mat for an 16x24" photo, choose the 20x28" (48x70cm) frame. The mat will have an 16x24" (40x60cm) opening.
