Enter any 3 values (building length, building width, roof rise, and total roof surface area) into the calculator to determine the missing variable. This calculator assumes a symmetric hip roof with a uniform pitch on all sides (no overhangs included), where rise is the vertical height from the eave line to the ridge.

Hip Roof Calculator

Enter any 3 values to calculate the missing variable (rise = vertical height from eave to ridge)

Hip Roof Formula

The following formula is used to calculate the total sloped surface area of a symmetric hip roof with a uniform pitch on all sides (excluding overhangs), given the building length, building width, and the roof rise (vertical height from eave to ridge):

A = L \sqrt{W^2 + 4H^2}

Variables:

  • A is the total roof surface area (sloped area of all roof faces combined)
  • L is the building length (the dimension parallel to the ridge line)
  • W is the building width/span (the dimension perpendicular to the ridge line)
  • H is the roof rise (vertical height from the eave line to the ridge)

To calculate the hip roof surface area, compute √(W² + 4H²) and multiply the result by the building length L. (Equivalently, you can compute the slant height s = √((W/2)² + H²) and use A = 2Ls.)

What is a Hip Roof?

A hip roof (or hipped roof) is a roof design where all exterior sides slope downward to the walls. On rectangular buildings, the sloping sides typically meet along a horizontal ridge; on square buildings, they can meet at a single point (a “pyramid” hip roof). Compared with a gable roof, a hip roof generally offers better performance in high winds because it has no large vertical gable ends.

How to Calculate Hip Roof?

The following steps outline how to calculate the Hip Roof.

  1. First, determine the building length L (the dimension parallel to the ridge line).
  2. Next, determine the building width/span W (the dimension perpendicular to the ridge line).
  3. Next, determine the roof rise H (vertical height from the eave line to the ridge). If you know the roof pitch angle θ, you can compute H = (W/2) × tan(θ).
  4. Next, compute the slant height from eave to ridge: s = √((W/2)² + H²).
  5. Finally, calculate the total roof surface area: A = 2 × L × s (equivalently, A = L √(W² + 4H²)).
  6. After inserting the values and calculating the result, check your answer with the calculator above.

Example Problem:

Use the following variables as an example problem to test your knowledge.

Building length (L) = 40 ft, Building width (W) = 30 ft

Roof pitch angle (θ) = 30° ⇒ Rise (H) = (W/2)·tan(θ) = 15·tan(30°) ≈ 8.66 ft, and Area (A) = L·W / cos(θ) = 40·30 / cos(30°) ≈ 1,386 sq ft