Then divide this number by 2 to reflect the separate halves of the roof.
Roof hip length.
In the example at left the run is 10.
The ridge of a hip roof is equal to the length of the building minus twice the run plus the thickness of the rafter stock.
First subtract 1 1 5 inches 2 5 3 8 cm from the width measurement you just took to account for the thickness of the ridge board which will span the length of the roof between the individual rafters.
For many people being able to get the right kind of hip roof calculator is very important as knowing how to measure a hip roof is going to be vital to making sure that it turns out well.