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Free Roof Materials Calculator

Use this roofing material calculator to quickly figure out what materials you’ll need to order for a roofing project. Just enter the roof’s floor area, eaves overhang, roof pitch, and the price per square foot of material to see an estimate for roofing rolls and felt paper.

Easily plan for upcoming jobs, reduce waste, and give your roofing customers more accurate estimates.

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Disclaimer:

The outputs, any associated images or diagrams, any measurements, and any and all other information (collectively, the “Outputs”) are provided for informational purposes only and do not constitute a binding quote or professional advice. The Outputs are based on general assumptions and the information you provided, which may not reflect the actual specifications or condition of the subject of the calculation, particularly in the case of complex structures or inputs. Accuracy may also vary depending on location, as some data may be more complete in certain regions than others. Actual results or outcomes may vary significantly following an onsite inspection and detailed assessment by a qualified professional. Any auto-generated visuals are for illustrative purposes and may not accurately represent the subject of the calculation. The Outputs should not be relied upon as a final result or used as the sole basis for financial, renovation, operational, or strategic decisions. Jobber recommends consultation with a qualified professional before proceeding with any work, quotes, or financial decisions. Jobber and its affiliates make no warranties, express or implied, regarding the accuracy, completeness, or suitability of the Outputs, and to the fullest extent permitted by law, we disclaim all liability for any damages or losses arising from reliance on the Outputs.

How to use our roof materials calculator

Calculate the materials you need for a new roof, along with the associated total cost, by entering these details into our roof material calculator:

  • Floor area in square feet
  • Eaves overhang (distance that the roof’s edge extends past the side walls) in feet
  • Roof pitch by degrees, percent, or fraction (/12)
  • Price per square foot for any materials

Next, click “Calculate” to see how many rolls of roofing and segments of felt paper you’ll need to complete the roofing project.

With this calculator, you can predict your material costs when you’re pricing a roofing job. This makes it easier to give your clients an accurate estimate for their roofing construction project.


How to estimate roofing materials

Here’s how to estimate the roofing materials you’ll need for a job using our free calculator:

  1. Measure or calculate the floor area. Multiply the building’s length and width. For example, say you’re working on a home that measures 50 feet by 30 feet. This gives you a floor area of 1,500 square feet.
  2. Factor in the eaves overhang. The building’s eaves extend past its side walls, meaning you still have additional roof space to cover. In our example, the home’s roof extends 2 feet past the sidewalls on all sides. Add in that value as your overhang.
  3. Determine roof pitch. The steeper the roof, the more area you need to cover with roofing material. Our example home has a commonly used pitch of 6/12, which has a slope multiplier of 1.12. You can add the pitch fraction to the calculator.
  4. Multiply by material costs. Say your client’s chosen roofing material costs $5 per square foot. When you plug that into the calculator and click “Calculate,” you’ll see that the total cost of roofing materials is $10,206.75.

Note that this amount doesn’t include the cost of any other project materials you might need, like felt or nails. It also doesn’t factor in your labor costs, markup, or profit margin.


Other essential roofing materials

In addition to shingles, every roofing job requires a few other materials for proper installation. Here’s a quick overview of common roofing materials and how to calculate the roofing materials you’ll need:

  • Underlayment: Most roofs need one layer of felt paper or synthetic underlayment over the entire roof deck. A 15-pound felt roll covers roughly 400 square feet, while a 30-pound felt roll covers closer to 200 square feet.
  • Nails: Standard asphalt shingles use anywhere from 240 to 360 nails per square (100 square feet). Multiply your total squares by 240–320 to determine your nail count, then round up to account for waste.
  • Fasteners: Metal roofing or specialty shingles might need screws or clips instead of nails. Most manufacturers specify how many fasteners are needed per square.
  • Fascia: Fascia boards cost $7 to $22 per linear foot. Multiply that amount by the roof’s perimeter to get your cost for fascia.
  • Flashing: Measure around chimneys, skylights, valleys, and roof edges. Add up these lengths and purchase flashing accordingly, with a little extra for trimming and overlaps.
  • Sealant: Use roofing sealant around flashing, vents, and ridges. Sealing costs $1 to $4 per square foot, depending on the type of sealant you use.

READ MORE: Roofing tools list: everything you’ll need for your next roofing job


How to calculate roof area with this materials calculator

Use our roof area calculator to find the total area of a roof. All you have to do is combine its length, width, and pitch as shown below:

  1. Measure the length and width of each roof section using building plans or ground measurements, then multiply these numbers to find the base area. A section that’s 40 feet long and 35 feet wide equals 1,400 square feet.
  2. Specify the roof pitch in degrees, percent, or fraction. Steeper roofs have a larger surface area. The calculator automatically applies a pitch multiplier to adjust the base area for slope.
  3. If the roof has multiple sections, calculate each one separately and then add the areas together to find the total roof surface area.


How to measure roof area

You can measure the area of a roof by multiplying length by width, then factoring in the roof pitch. Here’s an example to explain how to measure for roofing materials using our roofing area calculator:

  • Say you’re building a roof with two equal planes. Each plane measures 38 feet by 32 feet, so each has an area of 1,216 square feet.
  • Each plane has a pitch of 6/12. The standard multiplier for this pitch is about 12%. This brings the square footage of each roof plan to 1,362 square feet, rounded up.
  • When you add the roof planes together, you get a total roof area of 2,724 square feet.

It’s easy to use our roof surface area calculator to find the size of a roof plane. If you’re working on an irregular or complex roof, break the roof into sections and measure

Frequently Asked Questions

Following these practical tips will give you a more reliable material list, reducing costly overorders and last-minute trips to the supplier.

• Use a roofing cost calculator for a quick ballpark estimate, then take detailed measurements for more exact pricing when you prepare the final quote.
• Measure each roof plane separately. Take dimensions and account for every slope, dormer, extension, overhang, and eave.
• Apply the correct pitch multiplier. Steeper pitches increase surface area, so make sure your roof materials calculator applies the right multiplier for each pitch.
• Include a waste allowance. Add an extra 10–15% to cover waste or damaged materials, especially if the roof has a complex layout.
• Round up to whole bundles. Shingles are sold by the bundle, so always round your bundle total up to the next full bundle.
• Verify the area coverage for each shingle bundle according to manufacturer specifications. Many bundles cover roughly 33.3 sq ft, but check the specific product.
• Keep units consistent. Use the same measurement system (inches/feet/meters) throughout calculations to avoid conversion errors.
• Double-check measurements and keep photos or marked plans to reduce the chance of running out of material.
• Estimate accessories separately, like felt paper, flashing, and fasteners. These aren’t covered by a shingle bundle count. Follow manufacturer specs for quantities.
• Factor in penetrations. Add material for chimneys, skylights, vents, and complex areas that need extra flashing and sealant.
• Allow lead time and check stock. Confirm supplier availability and delivery schedules before finalizing the order.
Use a roof pitch area calculator to determine your roof pitch multiplier, or check this list as a quick reference:

• 1/12: 1.0035 multiplier / 4.76° angle
• 2/12: 1.0138 multiplier / 9.46° angle
• 3/12: 1.0308 multiplier / 14.04° angle
• 4/12: 1.0541 multiplier / 18.43° angle
• 5/12: 1.0833 multiplier / 22.62° angle
• 6/12: 1.1180 multiplier / 26.57° angle
• 7/12: 1.1577 multiplier / 30.26° angle
• 8/12: 1.2019 multiplier / 33.69° angle
• 9/12: 1.2500 multiplier / 36.37° angle
• 10/12: 1.3017 multiplier / 39.81° angle
• 11/12: 1.3566 multiplier / 42.51° angle
• 12/12: 1.4142 multiplier / 45.00° angle
Choosing the right roofing material depends on the project’s budget, location, and design—as well as the customer’s preference. Here’s a quick overview of common shingle types and what to consider for each:

• Asphalt shingles are affordable, widely available, and easy to install on most residential roofs. They have a shorter lifespan than other, more expensive shingle types.
• Wood shingles or shakes have a natural appearance and provide good insulation, but they cost more and require more maintenance compared to asphalt shingles.
• Metal shingles are lightweight and weather-resistant, with a longer lifespan than most shingle types. They come at a higher-than-average price tag and can be noisier than other roofing types.
• Clay shingles are durable, low-maintenance, and suited for hot and coastal climates. They’re also more expensive to install because their heavier weight requires reinforced roof structures.
• Slate shingles are the longest-lasting shingle type available, and they have a high-end appearance. They’re also a more premium option, and they need to be installed by skilled roofing contractors.
Our roofing material estimator can help you find out how many bundles of shingles you’ll need for your next roofing project. If you’d like to do the math yourself, follow these steps:

1. Measure the total roof area in square feet.
2. Divide by 100 to convert that number into roofing squares.
3. Multiply by 3, since each square typically requires three bundles of shingles.

Add an extra 10–15% waste factor to make sure you don’t run out of shingles. Round up to the nearest whole number—that’s how many bundles of shingles you need.
To estimate how many rolls of roofing felt you’ll need, start by finding your total roof area in square feet. Then, divide that number by the coverage per roll.

Coverage varies based on the type and weight of felt, but a 15-pound felt roll covers about 400 square feet per roll. 30-pound felt, on the other hand, covers about 200 square feet per roll.

Say your customer’s roof is 2,000 square feet and you’re using 15-pound felt. Divide 2,000 by 400, and you’ll see that you need 5 rolls of felt. To be safe, add 10–15% extra (in this instance, one extra roll) for overlap and waste.
Standard asphalt shingles use 240–360 nails per square, although some shingles require more. You’ll want a higher amount if the customer lives in a windy area or wants a type of shingle that typically needs more nails.

A 2,000-square-foot roof is 20 squares. Multiply by 240–360, and you’ll likely need 4,800–7,200 nails to complete the roofing job. To be safe, add an extra 10–15%, bringing the total to 5,280–8,280 roofing nails.