Measuring 27x35cm, 11x14" 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 11x14", you'll need at least 792 x 1008px and ideally 3300 x 4200px.
If you are looking for a frame with a mat for an 11x14" photo, choose the 15x18" (38x45cm) frame. The mat will have an 11x14" (27x35cm) opening.
