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Home/Calculators/Roofing Calculator
Calculators

Roofing Calculator

Estimate gable, shed, simple hip or measured-section roof area, roof squares and whole material packages with pitch-aware geometry.

  • ⚡FastRuns in your browser
  • ◆PrivateFiles stay on your device
  • ♥FreeNo account required

01 / PURPOSE-SPECIFIC INPUTS

Roof geometry and supplier material coverage

Advanced assumptions & optional details
Practical examples

02 / RESULT & INTERACTIVE INSPECTION

Your result, visual model and supporting work

Calculated roof surface before material waste1,502.638 ft²Displayed figures round independently from the underlying calculations. Inspect assumptions and model limits alongside the result.
Surface area
139.5996 m² / 1,502.6377 ft²
Roof squares · 100 ft² each
15.0264
Waste-adjusted order area
1,652.9014 ft²
Whole bundles / packages
50
Shingles in purchased bundles
1050
Optional material cost
$1,750.00
Illustrated first-section pitch
6:12 / 26.565051°

Material quantities are estimates. The hip model is restricted to simple equal-pitch rectangular geometry; complex roofs need measured sections. Ridge caps, valleys, flashings, overlaps, labor and structural design are not automatically included.

Roof projection and slope cross-section

42 ft × 32 ft · horizontal projectionExpanded dimensions include entered overhangRun 16 ft; rise 8 ftPitch 6:12 · 26.565°

Gable slope A: 751.319 ft² of roof surface.

Plan and cross-section each use a uniform length scale; they are separate views. The section view shows one run, not a perspective rendering. Custom mode illustrates its first section and retains every independently measured area in the selector/table. Complex intersections are not inferred.
Formula, worked explanation & limitations
  1. For a plane with pitch p:12, surface area = horizontal projected area × √(1+(p/12)²). Overhang is a horizontal extension on all four building sides, applied before slope correction.
  2. A gable has two equal slopes; a shed has one slope across the full expanded width. The simple hip model is a rectangular equal-pitch, equal-eave-height roof with ridge length = longer expanded dimension − shorter expanded dimension. Its two trapezoids and two triangles partition the horizontal footprint; it is not a model of intersecting hips, valleys or dormers.
  3. Custom sections are independent rectangular horizontal projections with their own pitch, including any overhang already measured. Overlapping projections must not be counted twice. The diagram illustrates the first section; the area breakdown retains every section.
  4. 1 foot = 0.3048 m exactly; 1 ft² = 0.09290304 m². A roof square is 100 ft², not a square meter. Waste is added once at 10%.
  5. Whole packages = ceiling(waste-adjusted area / entered coverage per package). Coverage is a supplier assumption; purchased shingle count = packages × entered shingles per package, not a layout-based shingle takeoff. Cost uses whole bundles or waste-adjusted area as explicitly selected.
Roof face / section area breakdown
Roof face / section area breakdown
Face / sectionSurface area · selected length unit squared
Gable slope A751.31884 ft²
Gable slope B751.31884 ft²

How to use Roofing Calculator

  1. 1
    Choose the calculation mode and enter its known values

    Enter your values locally; no inputs are uploaded.

  2. 2
    Calculate, then inspect the labeled visual and worked steps

    Check validation feedback before reviewing the browser-generated result.

  3. 3
    Compare assumptions and copy the result if useful

    Review the explanation, copy supported outputs or reset the workspace.

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About Roofing Calculator

Horizontal projected area is multiplied by sqrt(1 + (rise/12)²), or equivalently divided by cosine of slope angle. Horizontal overhang expands both building dimensions before the correction.

Benefits

Estimate gable, shed, simple hip or measured-section roof area, roof squares and whole material packages with pitch-aware geometry. Inspect the calculated data through labeled controls and review worked assumptions before using a result.

Privacy note

Roofing Calculator calculations run locally in browser memory. Entered financial values, wages, measurements and other inputs are not sent to a third-party processing service or saved as a personal profile. Ordinary website page requests may still be logged. Clipboard access happens only when you choose Copy Result.

Frequently asked questions

How is sloped roof area calculated?

Horizontal projected area is multiplied by sqrt(1 + (rise/12)²), or equivalently divided by cosine of slope angle. Horizontal overhang expands both building dimensions before the correction.

What assumptions does the hip model require?

It is a simple rectangular equal-pitch roof with equal eave heights. The ridge equals longer expanded dimension minus shorter expanded dimension, and two trapezoids plus two triangles partition the footprint. Complex hips, valleys and dormers need measured sections.

How are custom sections interpreted?

Each is an independent rectangular horizontal projection with its own pitch, including any overhang already measured. Do not overlap projected areas or add overhang again. The diagram illustrates the first section while the table retains every area.

What is a roof square?

One roof square is 100 square feet. One foot is exactly 0.3048 meters and one square foot is 0.09290304 square meters; a roof square is not one square meter.

How are bundles and shingle counts estimated?

Add the entered waste percentage once, divide by supplier coverage per bundle, then round up to whole bundles. Purchased shingle count is bundles times entered shingles per bundle, not a detailed course-by-course takeoff.

What does optional material cost include?

It uses either whole-bundle count times bundle price or waste-adjusted area times entered area price. It does not automatically include labor, flashing, ridge caps, fasteners, tear-off or a structural design allowance.