How to measure for an entry door? To get a general measurement open the door and measure the inside dimension where the door is hinged off of (all the way to the strike side). These measurements are typically 30″,32″, 36″ and sometimes even 42″ for a single entry door. Whatever the inside dimension is you want to add 1-1/2″ to determine the net frame dimension of your door with the frame size. In order to determine the height you will keep the door open and measure from the bottom not including the threshold. If you are on a raised foundation, you will measure from on top of the large wood sill, then measure all the way to where the door sits on the top frame. That measurement + 3/4″ for the top frame will give you the height’s net frame dimension. A Standard size for the height of most entry doors that are in stock are 81 3/4″. On units that are double doors: typical sizes for the inside dimension are usually 60″, 72″ and sometimes 64″. You will measure just like on the single door from one side to the other side and add 1-1/2″ to get the net frame dimension.