How many bundles of shingles are in a square?

Most architectural shingles run three bundles per roofing square (100 square feet); some heavier lines use four.

What is a roofing square?

A roofing square equals 100 square feet of roof surface. Materials and labor are almost always quoted per square.

Roofing Calculator

Estimate roofing squares, shingle bundles and underlayment for any roof.

100% free to useNo sign-up requiredImperial & metric units

How many bundles of shingles do I need?

To find how many shingle bundles you need, multiply the roof footprint by the pitch factor, divide by 100 to get roofing squares, then multiply by 3 bundles per square. A 40 ft by 30 ft footprint at a 6:12 pitch is about 13.4 squares, or roughly 40 bundles of architectural shingles plus waste for hips and valleys.

Inputs

Footprint lengthft

Footprint widthft

Roof pitch

Steeper pitches add hidden surface area.

Bundles per squarecount

Waste allowanceApplied to material quantities

Results

Roofing Squares

13.42 sq

1 square = 100 sq ft

Roof Surface

1,342 sq ft

Shingle Bundles

Underlayment Rolls

2 squares per roll

Estimates update instantly as you type. Confirm against local code before ordering materials.

Roofing is bought by the square, but your tape measure reads the ground, and the pitch of the roof hides real surface area. This free roofing calculator applies the correct slope factor so your square count, shingle bundles, and underlayment match the actual roof, not just its footprint.

A steeper pitch can add anywhere from five to over forty percent of surface area beyond the building footprint, which is exactly where under-ordering happens. Pick your pitch, set the bundles per square for your shingle line, and add a waste allowance for hips, valleys, ridge cap, and starter courses.

How roofing material is calculated

Footprint area is multiplied by a pitch factor to get the true roof surface, then divided by 100 to convert to roofing squares. Bundles and underlayment scale from total squares plus waste.

Squares = (Footprint ft² × Pitch Factor) ÷ 100

Roof pitch multiplier reference

How much the roof pitch adds to the flat footprint area.

Pitch	Multiplier	Added area
4:12	1.054	about 5%
6:12	1.118	about 12%
8:12	1.202	about 20%
12:12	1.414	about 41%

One roofing square equals 100 sq ft. Most architectural shingles run 3 bundles per square.

How to use it

1Enter the building footprint length and width in feet.
2Select the roof pitch to apply the correct slope factor.
3Read the roofing squares, shingle bundles and underlayment rolls.
4Add 10–15% waste for hips, valleys and starter courses.

Key terms explained

Roofing square: A unit equal to 100 square feet of roof surface. Materials and labor are quoted per square.
Pitch factor: A multiplier that converts flat footprint area into true sloped roof area based on the roof angle.
Bundle: A wrapped package of shingles. Most architectural shingles run three bundles per square.
Underlayment: The water-resistant layer beneath shingles. A standard roll covers about two squares.

Worked examples

Simple gable roof

A 40 ft × 30 ft footprint at a 6:12 pitch is about 13.4 squares, or roughly 40 bundles of architectural shingles.

Garage roof

A 24 ft × 24 ft footprint at 4:12 works out to about 6.2 squares.

Pro tips from the field

1Measure the footprint accurately, then let the pitch factor do the slope math, do not eyeball it.
2Order ridge cap and starter strip separately; they are not included in the field shingle count.
3Add more waste for cut-up roofs with many hips and valleys than for a simple gable.
4Confirm bundles per square for your exact shingle, premium lines sometimes use four.

Common mistakes

Estimating from the footprint without applying the pitch factor.
Forgetting extra material for hips, valleys, ridge cap and starter strip.
Ordering three bundles per square for every shingle, some lines run four.

Where it gets used

Reroof estimates

Convert a building footprint into squares and bundles for a tear-off and replace.

Garages and outbuildings

Quickly size smaller, simple gable roofs.

Budget planning

Get a square count to price materials before scheduling a crew.

Frequently asked questions

Free Roofing Calculator for Squares & Shingles

Roofing is sold by the square, but measurements come off a footprint, and the roof pitch can add 5 to 30 percent of hidden area. This free roofing calculator applies the correct slope factor so your square count, shingle bundles and underlayment match the real roof.

Use the pitch selector to convert your ground footprint into true surface area, then add a waste allowance for hips, valleys, ridge cap and starter courses before ordering.