Hip Roof Calculator
Estimates the total surface area of a hip roof from the building length and width in feet and the roof pitch given as rise per 12 of run. The pitch is turned into a slope multiplier applied to the footprint area.
What this calculator does
The Hip Roof Calculator estimates your result instantly from the values you enter, using standard construction & home formulas. Estimates the total surface area of a hip roof from the building length and width in feet and the roof pitch given as rise per 12 of run. The pitch is turned into a slope multiplier applied to the footprint area. Calculations run in your browser, so nothing you type is sent to a server, and the output is an estimate rather than a certified or official figure.
Result
About Hip Roof Calculator
This hip roof calculator estimates the sloped surface area of a hip roof over a rectangular building. It builds a slope multiplier from the pitch — the square root of 144 plus the pitch squared, divided by 12 — and multiplies it by the footprint area (length times width).
The result is the roof surface area, useful for a first pass at sheathing or shingle quantities. It reports area only, not a full material list.
Formula & Mathematical Calculation
Roof Surface Area (ft²) = f(Building Length (ft), Building Width (ft), Pitch (rise per 12))
Calculated according to standard construction formulas implemented in the calculator core.
Calculation Example
For a building 40 ft long and 30 ft wide with a 6:12 pitch:
- Slope factor = √(144 + 6²) ÷ 12 = √180 ÷ 12 ≈ 1.118
- Roof surface area = 40 × 30 × 1.118 ≈ 1341.6 ft²
Key Benefits
- Turns footprint dimensions and pitch into a roof surface area estimate
- Accepts pitch in the familiar rise-per-12 format
- Applies the slope factor to the footprint so steeper roofs return more area
- Gives a quick area figure to start sizing sheathing or shingles
How to Use this Calculator
-
Enter the building length
Type the building length in feet into the Building Length (ft) field, for example 40. -
Enter the building width
Type the building width in feet into the Building Width (ft) field, for example 30. -
Enter the pitch
Type the roof pitch as rise per 12 of run into the Pitch (rise per 12) field, for example 6 for a 6:12 roof. -
Calculate
Press Calculate to see the estimated roof surface area in square feet.
Assumptions & Limitations
What the calculation assumes
- Every value you enter is treated as an exact, known amount.
- Any rate or interval you enter is assumed to hold for the whole period unless the form asks for it separately.
- Results use standard published formulas and account only for the values entered above.
- Rounding is applied for display; the underlying calculation uses your full precision.
- Results are returned in the same units you enter, unless the tool states the output unit.
What it does not cover
- Hip Roof Calculator produces a calculated result for reference and learning, not a certified or official measurement.
- Real-world outcomes differ when tolerances, rounding rules or local standards apply.
- Definitions and standards vary by region and change over time; verify the convention that applies to your case.
- Figures are only as accurate as the inputs you supply — check them before acting on the result.
- For work where the result carries real consequences, confirm it against an authoritative source.
Frequently Asked Questions
Free to use, no account needed. Calculations run in your browser, so nothing you type is sent to a server. Results are estimates — how we build and check our calculators.