Measure your inside leg measurement (this is the distance from the floor to your crotch) to the floor, subtract 3 inch (for mountain bikes, or 1inch for road bikes) then subtract 10″ (the average distance from the bottom bracket to the ground). This will give you the maximum frame size that you will need.
You can also refer to the seat height (it is measured from the floor to the top of saddle) we sate in the description, if your inside leg measurement plus 10cm (the distance from the floor to the lowest point of the pedal) is in the range of seat height then it is fine for you.