What is a roofing square?

100 sq ft of roof surface. A roof with 2,236 sq ft of surface is 22.36 squares.

What are the pitch multipliers?

3/12 is 1.031, 4/12 is 1.054, 5/12 is 1.083, 6/12 is 1.118, 7/12 is 1.158, 8/12 is 1.202, 9/12 is 1.250, 10/12 is 1.302 and 12/12 is 1.414. Each is the square root of (1 + (rise / 12) squared).

How much waste should I add?

About 10 percent on a simple gable, 15 percent with hips and valleys, and up to 20 percent on a cut-up roof. Pick the roof type and the calculator sets the default.

How many bundles are in a square?

Typically 3 bundles per square for architectural shingles, about 33 sq ft each. Products differ, so check the wrapper and change the bundles per square to match.

Is this number a quote?

No. It is an estimate to help you plan and build your bid. Confirm the final quantity with your supplier before you order.

Free calculator

Roofing squares calculator

Multiply the plan area by the pitch multiplier, the square root of (1 + (rise / 12) squared), then divide by 100. A 2,000 sq ft plan area at 6/12 is 2,236 sq ft of roof, or 22.36 squares before waste.

Your job

Plan area

Plan area, overhangs included

The footprint seen from above, not the sloped surface.

Pitch

Rise per 12 in of run

Waste and bundles

Waste factor10%

10 percent on a simple gable, 15 percent with hips and valleys, up to 20 percent on a cut-up roof.

Bundles per square

Typically 3 for architectural shingles. Check the wrapper.

The pitch to scale, and the plan area stretched into roof area.

Squares with waste

24.60squares

22.36 squares plus 10 percent

Before waste

22.36squares

Roof area

2,236sq ft

Pitch multiplier

1.1180

6.00/12

Bundles

74bundles

At 3 per square, rounded up

The working, with your numbers

1. Pitch multiplier√(1 + (6.00 / 12)²)= 1.1180
2. Roof area2,000 x 1.1180= 2,236 sq ft
3. Squares2,236 / 100= 22.36
4. With waste22.36 x 1.10= 24.60
5. Bundles24.60 x 3, rounded up= 74

Typed those measurements in by hand?MetreMate measures them straight off your PDF plans. Free to start.

The formula, in plain words

1Pitch multiplier = square root of (1 + (rise divided by 12) squared). At 6/12 that is 1.118.
2Roof area = plan area in square feet times the pitch multiplier.
3Squares = roof area divided by 100 (one square is 100 sq ft of roof).
4Squares with waste = squares times (1 plus your waste allowance).
5Bundles = squares with waste times bundles per square, rounded up.

Worked example

A simple gable roof with 2,000 sq ft of plan area at a 6/12 pitch, 10 percent waste and 3 bundles per square.

1.Pitch multiplier: square root of (1 + 0.5 x 0.5) = square root of 1.25 = 1.1180.
2.Roof area: 2,000 x 1.1180 = 2,236 sq ft.
3.Squares: 2,236 / 100 = 22.36 squares.
4.With 10 percent waste: 22.36 x 1.10 = 24.60 squares.
5.Bundles: 24.60 x 3 = 73.8, rounded up to 74 bundles.

Answer: 22.36 squares of roof, 24.60 squares with waste, about 74 bundles at 3 a square.

Measured this off a plan? Do it in MetreMate

Upload the PDF, set the scale and measure on screen. MetreMate gives you the square feet, linear feet and counts off the plan; then you apply the thickness, pitch, waste or sheet size here. Runs in your browser, free to start, no credit card.

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How to measure it

Measure the roof's plan area (the footprint seen from above, overhangs included) in square feet off the roof plan.
Read the pitch off the elevations or the roof plan, as rise in inches per 12 in of run.
If parts of the roof have different pitches, run each part separately and add the squares.

Where the numbers come from

Every default in the calculator comes from a published source. We list the source next to it so you can check.

What	Value	Source
One roofing square, measured on the roof surface	100 sq ft per square	Vertigraph, how to calculate roofing squares (checked 2026-09-20)
Pitch multiplier = square root of (1 + (rise / 12) squared)	1.118 at 6/12	Vertigraph, how to calculate roofing squares (checked 2026-09-20)
Waste on a simple gable roof	10 percent	Vertigraph, how to calculate roofing squares (checked 2026-09-20)
Waste on a roof with hips and valleys (up to 20 percent on cut-up roofs)	15 percent	Vertigraph, how to calculate roofing squares (checked 2026-09-20)
Typical for architectural shingles (about 33 sq ft a bundle); check the wrapper	3 bundles per square	Vertigraph, how to calculate roofing squares (checked 2026-09-20)

Manufacturers named here are the source of the number, not a recommendation. Confirm quantities with your supplier.

Frequently asked questions

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