Use the drop down menu to pick which side of the door you will need hinge holes drilling, imagine you're looking at the outside face of the door when selecting the side for the hinge holes.

Next use the fields that appear under the dropdown menu to enter the distance from the top and bottom of the door that you want the hinge holes drilled (minimum 28mm to hinge centre).
We recommend 3 hinges for doors over 1000mm high or 1000mm wide for top hung. We recommend 4 hinges for doors over 1700mm high.