Roof Replacement Cost Estimator- How Do I Calculate The Cost of A New Roof

How do I calculate the cost of a new roof?

Opting to do a roof replacement is a hard decision for many homeowners because there are too many factors to consider. The roofing cost is the first factor that rings a bell whenever you imagine that your house needs a new roof or repair. But there is no bulletproof method for determining how much it will cost to give your home a modern look. However, the process has become easier over the years since many people can access an online roofing estimate calculator.

Image of Roof replacement cost estimator

Many of the available estimation tools use the size of the roof as a primary factor. Therefore, you need to know your house’s size, at least if you can determine a precise estimate.

How do you calculate the area of a roof?

Various methods can be used to calculate the area of your roof. Traditionally, roofing companies apply a multiplication factor to the square area of the house. The case is the same for both local companies and an online roof replacement cost estimator you may come across. Although there is not a common factor agreed upon by companies, many tend to use 1.5. Therefore, taking a simple house design where the measurements are length x width, the roof area would be (l x w) x 1.5. With this arrangement, a house with a floor measuring 3000 square feet would have a 4500 square foot roof.

Another roof area calculation method and one that is more accurate relies on the roof slope height. With this method, you take each section of your house design and multiply the roof slope height with the section length. For a simple design like the one we used in the previous method, the roof area is calculated as (slope height x house length) x2. Note that the value is multiplied by two because the house has both front and back roof slopes. However, for intricate house design, the calculation is not straightforward, and the roof area is a sum of the various sections.

How many squares is my roof?

Roofing companies do not use the roof area’s absolute value to estimate the cost or the number of roofing materials needed. Instead, they use a standard value referred to as the roofing square, where one roof square is equivalent to 100 square feet of the floor. That is to say that our simple example house with 3000 square foot floor has (3000/100) =30 squares. Therefore, the homeowner would have to buy 30 squares of shingles to replace the entire roof. This principle will hold even when you don’t have to use shingles for the roof because this is the primary value used by a roofing replacement cost calculator.

Is the square footage of a house the same as the roof?

The square footage of the house is not equivalent to that of the roof. Note that the roof has a pitch on both the front and the rear of the house. The pitch is often called the slope, and it significantly affects the square footage of the roof. Like we have previously indicated, a popularly used estimation method assumes that the roof footage is larger than the house’s square footage by half.

You can generally calculate the roof footage by feeding the necessary house measurements into a roofing estimate calculator. Someone can read these values from the house plan you obtained while buying your house. You can also get the house pan from the local housing department if you never received a copy from the seller.

How is drone roof measurements done?

The traditional roof area estimation methods are slowly becoming obsolete, and we are not likely to use them beyond the next few years. Drone technology makes it straightforward to inspect roofs without doing any calculations on paper or having someone climb there. So, if you have a tall house and are worried about how to estimate roofing cost, then drone roof measurement could be your salvation.

With this technology, a roofing company uses a drone and a compatible roof size estimation software to accomplish the task. The drone controller flies it high above the house and ensures that a clear image is captured. A high altitude is necessary to ensure the entire roof can be seen on a small screen like a laptop or tablet without scaling. Once you have the image, the next step involves determining the object’s scale to the drone-captured image. You can easily calculate the scale by measuring the house’s length and dividing it by the size captured in the picture.

With drone roof measurements, most of the work is done on the roof estimation software interface. Generally, some of the best roofing estimation software will allow you to trace the lines on the roof’s image. The lines’ length is automatically recorded, making it easy to calculate even complex rooftops’ roof size. Tracing lines on the roof often results in shapes whose area can be calculated easily, and you would need to sum the area of all the parts obtained to get the actual size. Remember, the calculations are done to scale, and you will have to convert based on the image scale we previously calculated.

Best roofing estimating software samples

If you are for the idea of buying a drone for your roofing company or for regularly inspecting your roof, then you better use superior quality software in combination. Knowing what to look for is the first step to making an excellent choice for the best roofing estimating software.

• Training and support

• Roofing estimation features

• Flexibility in use cases

Here are some roofing estimating software samples we know.

1. Roof Snap

Roof Snap is an estimation software that can be used to calculate costs based on images captured from a drone. The software allows you to trace roofing lines and calculate the roof’s actual size, from which you can then determine the quantity of materials needed. Note you may have to make considerations for labor costs since it is not accounted for.

2. DronePloy

Drone Ploy is a highly efficient roof inspection and measurement software. It is a scalable solution that provides you with accurate reports and precise roof measurements.

3. AppliCad

The AppliCad drone software works in the same principle as DronePloy and Roof Snap to measure, inspect, and document roof details from drone images. The application is connected to the cloud and is easy to use on any platform.

You can also use traditional estimation software like Microsoft Excel and others that don’t rely on the roof’s images, but then they would give you too much work.


Calculating the cost of a new roof is not a straightforward task, especially for homeowners. However, with the right mindset and some commitment, you can easily calculate the costs by yourself or seek a roofing company’s services. The easiest estimation method involves multiplying the square footage of a house by 1.5, a widely used constant in the industry. However, this method does not provide accurate measurements and may be inappropriate for complex roof structures. A drone-based roof replacement cost estimator is a better solution in the latter case and would yield more accurate estimates.



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