Roofing Calculator

Roofing & Exterior

Roofing Calculator

Estimate roof area, roofing squares, shingle bundles, waste and material cost.

Roof Details

Roofing Estimate
15 squares
Approximately 45 shingle bundles
Roof Area1,350 ft²
With Waste1,485 ft²
Bundles45
Estimated Cost—
Complex valleys, hips, dormers and roof shape can materially increase waste. Measure actual roof planes when possible.

How Much Roofing Do I Need?

This calculator estimates the surface area of a simple gable roof from the building dimensions, roof pitch and overhang.

What Is a Roofing Square?

Roofing materials are often measured in squares.

1 roofing square = 100 ft² of roof area

How Roof Pitch Changes Area

A sloped roof has more surface area than the flat footprint of the building. The calculator applies a pitch factor based on the selected rise per 12 inches of horizontal run.

Complex roofs: Hips, valleys, dormers, intersecting roofs and irregular shapes should be measured plane by plane for a better estimate.

Shingle Bundles per Square

Many asphalt shingles require approximately three bundles per square, but not every product uses the same packaging. Enter or verify the bundle requirement for your selected shingle.

Example

A 40 ft by 30 ft building with a 4/12 roof pitch and 1 ft overhang has a roof surface larger than the 1,200 ft² building footprint.

After pitch adjustment and waste, the calculator converts the result into roofing squares and then into shingle bundles.

Frequently Asked Questions

How much roofing waste should I add?

Waste depends heavily on roof complexity. Simple gable roofs may require less than roofs with many valleys, hips and dormers.

Does this calculate underlayment or flashing?

No. Underlayment, drip edge, flashing, ridge materials and ventilation should be calculated separately.

Can I use this for a hip roof?

It can provide a rough starting point, but measuring each roof plane individually is more appropriate for complex roof geometry.

Planning estimate: Roofing work involves fall hazards and weatherproofing requirements. Verify dimensions and installation requirements with qualified professionals.

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