How to Calculate Bundles of Shingles Needed

Updated 11 November 2026 · Standard formula, shown below

This guide walks you through calculating how many bundles of shingles you need for a roofing project. You’ll measure your roof, account for waste, and convert the total area into bundles—the unit shingles are sold in. By the end, you’ll have a number you can take to the supplier with confidence.

What You’ll Need

Tape measure (at least 25 ft / 7.5 m long)
Ladder or access to the roof (or use satellite measurements if you can’t climb)
Calculator
Paper and pencil to sketch the roof planes
Roof pitch gauge or a smartphone app with an inclinometer (optional but helpful)

Step-by-Step

Sketch each roof plane. Draw a simple rectangle for each flat section of your roof. A hip roof will have four planes; a gable roof will have two. Label each plane (A, B, C, etc.).
Measure the footprint of each plane. For each rectangle, measure the length and width in feet. For example, the front of a house might be 40 ft wide and the depth from eave to ridge might be 20 ft. Write down these numbers.
Adjust for roof pitch. The footprint area is the flat projection. You need the actual sloped surface area. Multiply the footprint area by a pitch factor: for a 4/12 pitch use 1.054, for 6/12 use 1.118, for 8/12 use 1.202, for 10/12 use 1.302. If you don’t know the pitch, you can measure it with a pitch gauge or use an app on your phone. For a low slope (2/12) the factor is about 1.014; for a steep 12/12 it’s 1.414.
Calculate the area of each plane. For each plane, multiply length × width × pitch factor. For a 40 ft × 20 ft plane at 6/12 pitch: 40 × 20 = 800 sq ft, then 800 × 1.118 = 894.4 sq ft. Round to the nearest whole number.
Add all plane areas together. Sum the adjusted areas from every plane. This is your total roof area in square feet.
Convert to squares. Roofing is measured in “squares” where 1 square = 100 sq ft. Divide your total area by 100. For example, 2,500 sq ft ÷ 100 = 25 squares.
Add waste allowance. Standard practice is to add 10% for waste (cutting, fitting, mistakes, and future repairs). Multiply your squares by 1.10. If you have a complex roof with valleys, dormers, or lots of penetrations, use 15% (multiply by 1.15). For a simple gable roof, 5% may suffice, but 10% is safer.
Convert squares to bundles. Most architectural shingles (the common laminated type) come 3 bundles per square. 3-tab shingles are often 4 bundles per square, but they are less common now. Check the label on the shingle you plan to buy—it will state bundles per square. For standard 3-bundle shingles, multiply your squares (with waste) by 3. For 25 squares with 10% waste: 25 × 1.10 = 27.5 squares, then 27.5 × 3 = 82.5 bundles. Round up to 83 bundles.
Round up to the nearest full bundle. Always round up, never down. If you get 82.5, buy 83. It’s better to have a few extra than to run short mid-project.

Common Mistakes

Forgetting the pitch factor. Many people measure the footprint and skip the slope adjustment, underestimating the area by 5% to 40% depending on steepness.
Ignoring waste. Even a simple roof has cuts at ridges, hips, and valleys. Without a waste allowance, you’ll likely run short.
Assuming 3 bundles per square for every shingle. Some heavy architectural shingles are 4 bundles per square, and some specialty products differ. Always read the label.
Mixing units. If you measure in meters, convert to feet (1 m = 3.28084 ft) before calculating squares, or use square meters and convert (1 square = 9.29 sq m).
Not measuring all planes. Dormers, overhangs, and small sections are easy to overlook. Include every surface that will be shingled.

Tips

Use a roofing calculator app or online tool to double-check your math.
If you can’t climb, use a satellite measurement from a mapping service or measure from the ground with a long tape and a ladder for the ridge height.
When buying, ask the supplier if they accept returns of unopened bundles—most do, so you can buy a little extra without risk.
Include the starter strip and ridge cap in your order. Starter shingles are often sold separately, and ridge caps are usually cut from standard shingles (one bundle covers about 20 linear ft of ridge).
Write the bundle count on your sketch and keep it for reference when you order.

Troubleshooting

Your calculated bundles seem too high or too low. Re-measure the length and width of each plane. A common error is mixing up feet and inches. For example, 20 ft 6 in is 20.5 ft, not 20.06 ft. Also verify the pitch factor—a 6/12 pitch is 1.118, not 1.16.

You have a complex roof with valleys and hips. The 10% waste may not be enough. Use 15% or even 20% if there are many valleys, dormers, or unusual angles. It’s safer to overestimate slightly.

The shingle label says “4 bundles per square” instead of 3. Adjust your final multiplication accordingly. If you already bought shingles, check the label on the bundles you have.

You measured in meters and now have a number in square meters. Convert to squares: 1 square = 9.29 sq m. Divide your square meters by 9.29 to get squares, then proceed.

You can’t determine the roof pitch. Use the default factor of 1.15 (about a 7/12 pitch) as a middle ground, or measure the rise and run: pitch = rise / run in inches per foot. For example, if the roof rises 6 inches for every 12 inches of horizontal run, that’s 6/12.

Frequently Asked Questions

Q: How many bundles of shingles do I need for a 1,000 sq ft roof?
A: For a 1,000 sq ft roof (10 squares), with 10% waste you need 11 squares. At 3 bundles per square, that’s 33 bundles. If the pitch is steep, adjust the area first.

Q: What is a “square” of shingles?
A: A square is a roofing term for 100 square feet of shingle coverage. It’s the standard unit for ordering roofing materials.

Q: How much does one bundle of shingles cover?
A: A standard bundle of architectural shingles covers about 33.3 sq ft (since 3 bundles cover 100 sq ft). A 4-bundle-per-square product covers 25 sq ft per bundle.

Q: Do I need to include the starter strip in my bundle count?
A: Starter strip is usually sold separately or as a roll, not as bundles. You’ll need to order starter separately—roughly one bundle per 200 linear ft of eave. Ridge cap shingles are typically cut from standard bundles; one bundle covers about 20 linear ft of ridge.

Q: Can I return extra bundles?
A: Most roofing suppliers accept returns of unopened, undamaged bundles within 30 days. Check with your supplier before buying to confirm their policy.

Q: What if my roof has a very steep pitch?
A: Steeper roofs have more surface area and require more shingles. Use the correct pitch factor (up to 1.414 for 12/12) and consider adding extra waste because working on a steep roof often leads to more cutting and dropped shingles.

Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.