Roof measurement
Hip rafter length calculator
Estimate hip rafter geometric length. One equal-pitch hip runs from an outside plan corner to a ridge endpoint.
Try the calculation
Use the plan offsets and vertical rise between the hip endpoints.
Adjustable example. Change these illustrative inputs to match your task, then recalculate. Reset restores the example and its result.
Understand the result
How this calculation works
Hip centerline length is the three-dimensional distance between the measured plan offsets and rise.
Steps
- Enter plan offset X, plan offset Y and vertical rise for the same hip endpoint pair.
The form starts with the worked example below. Change its values and selections to match your task; Reset restores the example.
Formula
length = √(x² + y² + rise²).
Variables and units
- Plan offset X (ft)
- Required. Use a positive value. Starting example: 15. Replace it for your task.
- Plan offset Y (ft)
- Required. Use a positive value. Starting example: 15. Replace it for your task.
- Vertical rise (ft)
- Required. Use a positive value. Starting example: 6. Replace it for your task.
What the result means
It is a geometric centerline. Cuts, overhangs and structural sizing are outside the result.
Worked example
Inputs: Plan offset X = 15; Plan offset Y = 15; Vertical rise = 6.
Calculation: √(15² + 15² + 6²) = 22.05 ft.
Result: 22.05 ft hip rafter centerline.
Frequently asked questions
Are X and Y the full roof dimensions?
They are the plan offsets used for this line.
Does this calculate hip material?
No, use the resulting measurement in a separate quantity takeoff.
Can the roof be irregular?
Measure the actual offsets before calculating the length.