Calculate hip roof length, width, rise or roof surface area from any 3 inputs using meters, feet, inches, square meters, square feet, or square yards.
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Hip Roof Formula
The calculator uses a simplified hip roof surface area model based on building length, building width, and vertical rise. It assumes the roof rises evenly from the eaves to the ridge and uses the total sloped roof surface area.
Rearranged formulas for solving each missing value:
- A = total roof surface area
- L = building length, measured parallel to the ridge
- W = building width or span
- H = rise, the vertical height from the eave to the ridge
If you leave the area field blank, the calculator finds the total roof surface area. If you leave length, width, or rise blank, it rearranges the same formula to solve for that missing value. Length, width, and rise are converted to meters internally, and area is converted to square meters internally before the final result is converted back to your selected unit.
Common Roof Pitch and Rise Reference
Roof pitch is often written as rise over 12 inches of run. The rise used in the calculator is the full vertical height from the eave to the ridge, not the pitch number itself.
| Pitch | Angle, Approx. | General Description |
|---|---|---|
| 3:12 | 14.0° | Low slope |
| 4:12 | 18.4° | Common residential slope |
| 6:12 | 26.6° | Moderate slope |
| 8:12 | 33.7° | Steeper roof |
| 12:12 | 45.0° | Very steep roof |
Area Unit Conversions
| Unit | Equivalent | Useful For |
|---|---|---|
| 1 square meter | 10.7639 square feet | Metric plans and measurements |
| 1 square foot | 0.092903 square meters | Common U.S. roof area estimates |
| 1 square yard | 9 square feet | Some material and covering estimates |
Examples
Example 1: Calculate roof surface area
Suppose the building length is 40 ft, the width is 24 ft, and the rise is 6 ft.
The total roof surface area is about 1,073.31 square feet.
Example 2: Calculate rise
Suppose the roof area is 1,073.31 sq ft, the length is 40 ft, and the width is 24 ft.
The rise is about 6 feet.
FAQ
What does rise mean for a hip roof?
Rise is the vertical distance from the eave line to the ridge. It is not the sloped rafter length and it is not the roof pitch by itself. If you know the roof pitch and the horizontal run, you can find rise from pitch before using the calculator.
Does the calculated roof area include overhangs?
The result only reflects the length and width values you enter. If you want the area to include overhangs, include the overhangs in the building length and width measurements. For example, a 40 ft by 24 ft building with 1 ft overhangs on all sides would use 42 ft by 26 ft as the outside roof footprint dimensions.
Why does the calculator say there is no real solution?
A no-solution result means the entered area is too small for the given length, width, and rise combination. For example, a roof with a larger rise must have more sloped surface area than the flat footprint. Check that the area, length, width, and rise use the intended units and measurements.
