How Many Shingles Do I Need?

Shingle roofs are affordable, weather-resistant, and attractive, making them a popular choice with homeowners. Whether you need to repair your asphalt roof or replace it entirely, you’ll need to know how many shingles you require. This calculator will help you measure your roof’s area and pitch and determine the correct number of shingles to buy for your project.

How Many Shingles Do You Need For Your Roof?

Roof shingles are sold in bundles, so you’ll need to determine the number of bundles you need based on the size and pitch of your roof. Below are some common roof sizes and pitches, along with the number of shingle bundles required for each.

Calculating How Many Shingles You Need

A bundle of shingles covers around 33.3 square feet, so you’ll divide the roof size by 33.3 to get the number of bundles needed. 

Plug your roof details into the following formula to calculate the number of shingle bundles you need. Multiply that number by 1.15 to account for waste. 

If you’re left with an uneven number, round up to determine how many bundles to buy.

How to Measure for Shingles

Measuring for shingles is a multi-step process. Here’s how to do it, broken out into three distinct steps.

1. Measure Roof Area

To calculate the number of shingles you need, you’ll first need to determine your roof's size. Here’s how to do that.

• Measure the length of your roof from one end to the other.

• Measure the width of your roof from the peak to the eaves.

• Multiply the roof length by the roof width to get the total area.

For example, if your roof measures 20 feet from one end to the other and 10 feet from the peak to the eaves, the total area is 200 square feet.

2. Measure Roof Pitch

Once you’ve measured the roof’s area, you’ll need to factor in the roof pitch. You can do that from the attic or the roof (as long as you have the proper safety equipment) as follows.

• From the attic, measure the height from the floor to the highest point on the roof. Then, measure the distance between the exterior walls and divide by two.

• From the roof, hold a 12-inch level against the roof surface and adjust until it’s flat. Then, measure the distance from the roof to the 12-inch mark on the level.

• Find the roof pitch multiplier in the table below and multiply that number by the roof’s area.

For example, a 200-square-foot roof with a 3/12 slope would measure 206.16 square feet.

3. Determine the Number of Shingles Needed

Once you have determined your total roof area, follow these steps to calculate the number of shingles needed.

• Divide the area of your roof by 33.3.

• Multiply that number by 1.15 to account for waste.

• Round up to get the total number of shingle bundles needed.

• Multiply the number of shingles per bundle by the number of bundles needed to get the total number of shingles you need for your project.

For example, a 206.16-square-foot roof would need 6.25 bundles of shingles for full coverage. After adding 15% for wastage, you’d need 7.18 bundles. You could either round down to 7 or up to 8. If each bundle contains 29 shingles, you’d need between 203 and 232 shingles total.

Who to Hire for Roof Shingle Installation

Roofing typically isn’t a DIY job. It involves working at great heights, which means it’s extremely hazardous. Without the proper experience and safety equipment, you risk severe injury or even death. Hiring a roofing contractor is the way to go. As you research the local options in your area, familiarize yourself with the right questions to ask a roofer before hiring them.