First, determine if your device has a raised bezel or a flat front glass screen.
These screens have a raised frame around the edges.
Next, measure your screen according to the screen type you have.
Measure the height (h) and width (w) of the screen's viewable area making sure to measure within the bezel.
Measure the height (h) and width (w) of the entire glass display making sure to measure all the way from edge-to-edge.