How many square feet are in a roofing square?

One roofing square equals 100 square feet of roof surface.

How many shingle bundles are in a square?

Many three-tab or architectural shingles use about three bundles per square, but always verify the bundle coverage on the product label.

How much waste should I add?

A simple gable roof may use about 10% waste. Hip roofs, valleys, dormers and complex cuts can need 12-15% or more.

Roofing Calculator

Estimate roof area, roofing squares, shingle bundles, underlayment, starter, ridge caps, nails, waste and basic material cost for a U.S. roofing project.

Roof type

Two roof planes with a ridge and two rake edges.

Building footprint

Length, ft

Length, in

Width, ft

Width, in

Pitch rise per 12

Overhang, in

Waste, %

Underlayment roll, sq ft

Shingle type

Packages per square

Material prices

Bundle price, $

Underlayment roll price, $

Nails price per lb, $

Roof slope preview

Estimate roofing squares and materials

English roofing-calculator results usually answer a material-estimating question first: how many roofing squares, shingle bundles, rolls of underlayment and fasteners are needed from roof dimensions and pitch.

A r e a_{r oo f} = A r e a_{pl an} \times P i t c h f a c t or

The pitch factor converts the flat building footprint into sloped roof area.

S q u a r es = \frac{A r e a _{r oo f}}{100}

One roofing square covers 100 square feet.

B u n d l es = ⌈ S q u a r es \times B u n d l es P er S q u a r e \times (1 + W a s t e) ⌉

Asphalt shingles are normally purchased by whole bundles.

What changes the final roof order

Roof pitch, valleys, hips, dormers, waste, starter course, ridge caps and local code details can change the final quantity.
Underlayment, ice barrier, flashing, drip edge, ventilation and tear-off are separate from the field shingles.
Use manufacturer instructions and local building-code requirements before purchasing or installing roofing materials.

Frequently Asked Questions

Sources and References

Calculations are based on the listed reference sources. Links open in a new tab.

Updated: May 29, 2026

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