Roofing

Roofing Calculator

Use this roofing calculator to estimate roof surface area, roofing squares and approximate shingle bundles for a simple gable roof. Enter the building footprint, roof pitch and waste allowance to convert horizontal area into sloped roof area.

✓ Free✓ Instant result✓ No signup

Step 1

Enter project details

Building length ft Building width ft Roof rise per 12 in/12 Waste allowance % Coverage per bundle sq ft

Planning estimate only. Confirm local prices, supplier specifications and site conditions before ordering.

Step 2

Your estimate

Footprint area—

Roof surface area—

Roofing squares—

Approx. bundles—

Simple footprint-and-pitch math is useful for planning, but complex roofs should be broken into individual planes and measured carefully before ordering.

Optional next step

Request a local roofing quote

Complete three short steps to check for available local professionals.

Free to submit No purchase required

How matching works

ProjectMetrica helps route your roofing installation or repair request to participating platform partners or service providers when an eligible match is available.

Availability depends on ZIP code, service and project details.
ProjectMetrica is not the contractor and may receive compensation for an accepted request.

ProjectMetrica collects this request and may share it with participating service providers and platform partners for the home-improvement project you selected. The consent session is independently recorded. See the Privacy Policy.

1 Project 2 Timing 3 Contact

Step 1 of 3

What kind of project is it?

Choose the service details and enter the five-digit project ZIP code.

Roof material Roofing project ZIP code

Step 2 of 3

When are you planning the work?

These details help make the request more relevant. No availability check is sent yet.

Hiring status Project timeframe Can you authorize work on the property? Project details

Step 3 of 3

Where can professionals reach you?

Use the contact details for the property where the project is planned. This usually takes about a minute.

Your request stays focused on this project

Your address helps check local service availability and is not posted publicly.
Submitting is free and does not require you to hire anyone.
Your details are used to process and route the home-service request described here.

First name Last name Project street addressEnter the street address where the work is planned. You can correct every address field before submitting. City State Phone Email

By submitting, you confirm that you are at least 18 years old and that the information you provided is accurate.

Your request may be sent to participating home-improvement providers when a qualifying match is available.

Before you order

Check local supplier specs

Density, bag coverage, pallet size and recommended installation depth can vary by material and supplier.

Professional installation

Compare local project quotes

Connect with a local professional for a site-specific estimate.

Get free quotes →

Formula & assumptions

How the roofing calculator works

Roof area = footprint area × pitch factor. Pitch factor = √(1 + (rise ÷ 12)²). Roofing squares = roof area ÷ 100, with waste applied before bundle quantity.

For a better estimate

This simple model works best for uncomplicated gable roofs. Valleys, hips, dormers and multiple roof sections should be measured separately.
Use actual roof dimensions where possible rather than relying only on interior floor area.
Roofing work can be dangerous; use professional measurement methods or contractor estimates when safe access is not available.

Useful project tools

Tools that can help with this project

Affiliate disclosure: As an Amazon Associate I earn from qualifying purchases.

Tape measureMeasure roof planes and material layout. View on Amazon → Chalk lineCreate straight layout reference lines. View on Amazon → Roofing nail pouchKeep small roofing tools and fasteners organized. View on Amazon →

Common questions

Frequently asked questions

How do I calculate roof square footage?+

Start with the horizontal footprint, multiply by a pitch factor and measure complex roof sections separately.

What is a roofing square?+

One roofing square equals 100 square feet of roof surface area.

How much waste should I add for shingles?+

Waste depends on roof complexity, shingle layout and cuts. Simple roofs generally need less than roofs with many valleys, hips or penetrations.

Enter project details

Your estimate

Request a local roofing quote

What kind of project is it?

When are you planning the work?

Where can professionals reach you?

Check local supplier specs

Compare local project quotes

How the roofing calculator works

For a better estimate

Tools that can help with this project

Frequently asked questions

Guides for this project

How to Measure a Roof for Shingles

Roofing Squares Explained: Square Feet, Bundles and Coverage

Roof Pitch Waste Factor: Planning Shingle Waste

How Many Shingles Do I Need?

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