Measuring 60x121cm, 24x48" 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 24x48", you'll need at least 1728 x 3456px and ideally 7200 x 14400px.
If you are looking for a frame with a mat for an 24x48" photo, choose the 28x52" (70x132cm) frame. The mat will have an 24x48" (60x121cm) opening.