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Hip Roof Calculator

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The Hip Roof Calculator is an essential tool designed to simplify the complex process of calculating the area of a hip roof. This type of roof, characterized by slopes on all four sides that come together at the top, requires precise calculations to ensure accurate material estimates and project planning. The calculator uses specific inputs and formulas to streamline these calculations, making it a valuable resource for architects, builders, and DIY enthusiasts alike.

Purpose and Functionality

The primary purpose of the Hip Roof Calculator is to provide an easy and accurate method for determining the total area of a hip roof based on a few key measurements. These measurements include the length and width of the building and the pitch of the roof. By inputting these values, the calculator performs a series of calculations to produce the total roof area, which is crucial for material estimation, cost calculations, and project planning.

Inputs Needed

  • Length of the Building (L): Measured as the distance from one end of the building to the other, along the ridge of the roof.
  • Width of the Building (W): Measured as the distance between the two sides of the building, perpendicular to the ridge.
  • Roof Pitch (P): Defined as the angle of the roof, typically represented as a ratio of vertical rise to horizontal run (e.g., 4:12).


  1. Convert Roof Pitch to an Angle (A): The first step involves converting the roof pitch ratio into an angle in degrees, using the formula A = atan(P_vertical / P_horizontal).
  2. Calculate the Rafter Length (R): This calculation determines the length of the beams supporting the roof, based on the half-length of the building and the roof’s angle.
  3. Calculate the Hip Length (H): Similar to the rafter length, the hip length calculation determines the distance from each corner of the building to the top of the roof.
  4. Calculate Total Roof Area: The final step adds together the areas of trapezoids and triangles formed by the rafters and hips to produce the total roof area.

Step-by-Step Example

Let’s go through a simple example to illustrate how the Hip Roof Calculator works:

  • Length of the Building (L): 20 meters
  • Width of the Building (W): 10 meters
  • Roof Pitch (P): 4:12

Using these inputs, the calculator will first convert the roof pitch into an angle, then calculate the lengths of the rafters and hips, and finally, compute the total roof area.

Relevant Information Table

InputSymbolExample Value
Length of the BuildingL20 meters
Width of the BuildingW10 meters
Roof Pitch (Vertical)P_vertical4 units
Roof Pitch (Horizontal)P_horizontal12 units
Angle of Roof PitchACalculated
Rafter LengthRCalculated
Hip LengthHCalculated
Total Roof AreaTotal_AreaCalculated


The Hip Roof Calculator is an invaluable tool for anyone involved in the construction or renovation of buildings with hip roofs. By simplifying complex calculations into a few straightforward steps, it not only saves time but also enhances accuracy in material estimation and project planning. Whether you’re a professional builder or a DIY enthusiast, this calculator ensures that you can approach your hip roof projects with confidence, backed by precise, reliable data.

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