Roofing Material Calculator – Estimate Bundles of Shingles and Squares

Calculate your roof’s size and estimate how many bundles of shingles, rolls of felt, and squares of roofing material you need for a new roof. Add the price per square for materials to get an estimated material cost.

Dimensions measured from the ground
find roof pitch
Optionally enter the price per square
*The average cost of materials for a standard 3-tab shingle is about $100 per square, including shingles, felt paper, and nails.

Roofing Material Estimate:

bundles of 3-tab shingles
rolls of 15lb felt
Estimated Material Cost
total cost
Installation Overview
square feet
Learn how we calculated this below

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How to Estimate the Size of a Roof

If you’re replacing a roof, the first consideration needs to be the roof’s size so you can accurately estimate project materials.

In the U.S., roofs are measured in square footage, and roofing contractors typically quote projects based on the size of the roof in squares. Consequently, gathering the size of the roof in squares and square footage is the first step.

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Find the Area of the Footprint of the Roof

Diagram showing how to measure a roof from the ground by measuring the building and accounting for the overhang of the roof.

To calculate a roof’s dimensions, you need to measure the roof as if it were flat, then account for roof pitch, calculate square footage, and finally determine how many squares of material are required for the roof.

The calculator above can handle all of this, simply enter the length, width, and pitch, and it will determine the size of the roof in squares.

Start by measuring the roof’s length and width in feet as you’re standing on the ground. Remember that the length and width need to be found for the roof, not the house, so take into account that the roof overhangs the building.

Then determine the area of the roof as if it were flat. Multiply the length by the width in feet to get the area measurement.

Finding the Total Roof Area

Once the area of the roof’s footprint is known, the overall roof area can be found by accounting for the roof’s pitch. The pitch of the roof is the rise over a 12-inch run. Use our roof pitch calculator to find the pitch of your roof.

Next, multiply the footprint of the roof by the multiplier below for your roof pitch to find the overall roof area.

For example, a 4/12 pitch roof that is 100 square feet:

100 × 1.054 = 105.4ft2

Roof Pitch Area Multipliers

Multipliers for common roof pitches that can be used to find the total area of a roof.
Pitch Multiplier
0/12 1
1/12 1.003
2/12 1.014
3/12 1.031
4/12 1.054
5/12 1.083
6/12 1.118
7/12 1.158
8/12 1.202
9/12 1.25
10/12 1.302
11/12 1.357
12/12 1.414
13/12 1.474
14/12 1.537
15/12 1.601
16/12 1.667
17/12 1.734
18/12 1.803
19/12 1.873
20/12 1.944
21/12 2.016
22/12 2.088
23/12 2.162
24/12 2.236

Finding the Size of the Roof in Squares

Roofing contractors estimate projects and materials by the square, so it is crucial to find this measurement to estimate the amount of material needed accurately. A square simply refers to a 10′ x 10′ square of roofing. This is simply 100 square feet of roof.

To find the squares, divide the overall roof area by 100 and then round up. For instance, if the roof is 1550 square feet, then it is 16 squares.

How to Estimate Roofing Materials

Although roofing projects are estimated and sold by the square, roofing material is often not sold in 1 square increments.

Roofing contractor installing asphalt shingle roof

How Many Bundles of Shingles Will You Need

The average bundle of shingles covers 33.3 ft2, so three bundles of shingles are needed per square. Asphalt shingles range in price from about $25 per bundle for a standard 3-tab style to around $50-$75 or more for an upgraded architectural style.

Since transportation is a major cost factor, expect prices to vary by location. A typical bundle of shingles weighs about 75 pounds, while some premium products can weigh over 100 pounds per bundle, so consider delivery of materials.

How Many Rolls of Felt Will You Need

Roofing felt is sold by the roll. The average roll of 15-pound roofing felt covers about 400 ft2, or 4 squares, while the average roll of 30-pound roofing felt covers about 200 ft2, or 2 squares.

Rolls of felt are 36″ wide x 144′ long for 15# and 72′ long for 30#. Consider other underlayment options as needed, such as rubber or tar products.

How Many Nails Will You Need

Nails will also be required for any roofing project. The average 3-tab shingle needs four nails per shingle. High wind areas and other types of shingles may need more. 320 nails will be needed to install a square of standard 3-tab shingles, assuming four nails per shingle and 80 shingles per square.

Other Materials

Keep in mind that a drip-edge will be needed to protect the roof’s edge from rot, vents, and other materials such as flashing or caulk. Also, consider that the fascia boards may need to be replaced depending on their condition.

Drip-edge and fascia boards are sold by the linear foot, find the perimeter of your roof in feet to find the length of drip-edge and fascia boards needed.

In addition to accurately estimating materials, it is important to make sure you order extra material when ordering. Account for about 5-10% overage on your project to make sure you have enough material if measurements are a little off or material is wasted or damaged. This is more critical for materials that are special-order or have long lead times.

We recommend getting free roofing estimates to understand material and labor costs and identify other project complexities that could affect the cost.

Other Considerations

There are some other factors to consider when installing a new roof. Learn about the costs of installing a new roof. Many localities require permits and inspections for roofing projects; check with your local inspections office and consult local building codes for more information on the requirements.

Also, consider that removing old materials may be a good idea and will require disposing of a large amount of waste. Plan ahead for this by ordering a dumpster for the project.