Roof measurement
Gambrel roof area calculator
Estimate gambrel roof area. Gambrel house or barn-like residential roof.
Try the calculation
Enter each upper and lower roof-plane area once, including both sides.
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
A gambrel estimate adds four measured planes: two upper and two lower.
Steps
- Measure both upper and lower planes on both sides.
- Enter each area once.
The form starts with the worked example below. Change its values and selections to match your task; Reset restores the example.
Formula
area = upper 1 + upper 2 + lower 1 + lower 2.
Variables and units
- Upper plane 1 (sq ft)
- Required. Use a positive value. Starting example: 400. Replace it for your task.
- Upper plane 2 (sq ft)
- Required. Use a positive value. Starting example: 500. Replace it for your task.
- Lower plane 1 (sq ft)
- Required. Use a positive value. Starting example: 700. Replace it for your task.
- Lower plane 2 (sq ft)
- Required. Use a positive value. Starting example: 800. Replace it for your task.
What the result means
The page adds measured planes and does not generate gambrel geometry from width, rise or pitch.
Worked example
Inputs: Upper plane 1 = 400; Upper plane 2 = 500; Lower plane 1 = 700; Lower plane 2 = 800.
Calculation: 400 + 500 + 700 + 800 = 2,400 sq ft.
Result: 2,400 sq ft.
Frequently asked questions
Can I use this for a barn roof?
Yes, when the four surface areas fit this model.
Does it infer the break between slopes?
No, measure each plane separately.
Should a dormer be added?
Add any separate roof surface using its own measured area.