Roofing Calculator

Thinking about installing a new roof on your home? Or do you want to replace the old one? One of the most crucial steps in this process is figuring out how much material you’ll need and how much it will cost you.

Getting these estimates is very important otherwise, you could end up buying too much or too little material. To help you with these estimates, our roofing calculator comes into play. This online tool requires some basic inputs to perform the calculation and gives you accurate estimates of materials you might need and their cost.

What Information You'll Need (Before Using This Calculator)

To get the most accurate results, you must gather the right information first. Here is what you need to prepare:

1. House Length:
First of all, you need to measure how long your house is. This is the distance from one side of your house to the other, usually along the longest side. To get the accurate results, you can use a measuring tape.

2. House Width:
Next, you need to measure how wide your house is. This is the distance from the front to the back, along the shorter side.

3. Roof Pitch:
The roof pitch refers to how sloped your roof is. You can measure this by looking at how much the roof rises over a certain distance. The steeper the roof, the higher the pitch. This measurement helps the calculator estimate the actual roof area, as steeper roofs need more material.

4. Price:
You’ll also need to know the price of the roofing materials you want to use. Prices can vary based on the material you choose, like shingles, metal, or tile. The calculator will use this price information to estimate the total cost of your roofing project.

How to Use a Roofing Calculator (Step-by-Step)

Once you have all the above information, now you’re ready to use the roofing calculator. Follow these simple steps to get started!

Step 1: Enter Your Roof Dimensions

• Input Length and Width:
  Choose the measurement unit and enter the length and width of your roof sections into their respective fields.

Step 2: Input the Roof Pitch

• Find the input area for the roof pitch.
• Enter the pitch value either as a:
  • Ratio or
  • Percentage

Step 3: Enter the Price Per Unit

• Your final step is to enter the per unit cost of the roofing material into its given section.

Step 4: Calculate and Review the Results

• Click “Calculate”:
  Once all fields are filled, click on the calculate button.
• Review Output:
  The calculator will display the estimated amount of materials needed such as house base area, pitch of the roof, total roof area, and cost.

How to Calculate Roofing Material?

It’s recommended to use the roofing calculator for instant and accurate results. But if you still want to calculate it manually, keep reading!

Key Formulas

You have to use these formulas to calculate the roofing material.

I. Base Area

The base area is the area of the roof as if it were flat (like the floor area of the house or building). The formula to calculate the base area of your roof is:

• Base Area = Length x Width

Ⅱ. Pitch (%)

To calculate the roof pitch in percentage form, use this formula:

• Pitch (%) = (x / 12) x 100

Here,

X – Roof Pitch Ratio

This represents the slope of the roof and can be expressed in ratios such as 4:12, 6:12, or similar formats.

Ⅲ. Pitch (deg)

Pitch (deg) is the angle of the roof slope expressed in degrees. Use this formula to calculate the pitch in degrees:

• Pitch (deg) = arctan (Pitch Ratio)

Here,

• arctan (Inverse Tangent Function) – The arctan (also written as tan⁻¹) is a trigonometric function that calculates the angle when the tangent of that angle is known.

Pitch Ratio – The pitch ratio represents the slope of the roof and is expressed as a ratio of Rise (vertical height) to Run (horizontal distance).

Ⅳ. Roof Area

It’s the total surface area of the roof that needs to be covered. The formula for calculating roof area is as follows:

• Roof Area = Base Area / cos [Pitch (deg)]

Here,

• cos – cos stands for cosine, a trigonometric function.

Ⅴ. Roofing Cost

This is the total cost required to cover the roof with materials. To calculate this, use the below formula:

• Roofing Cost = Unit Price x Roof Area

Here,

• Unit Price – This is the cost per unit area of the roofing material and is usually expressed as cost per square foot (sq ft) or cost per square meter (sq m).

Real-Life Example of Roofing Calculation

Let's work through a real-life example step by step:

Example Details

Let’s say you have the following values for your roofing calculation:

• House Dimensions (Base of Roof): 30 ft (length) by 20 ft (width)
• Roof Pitch Ratio: 4/12 (which means the roof rises 4 feet for every 12 feet horizontally)
• Cost of Roofing Material: $3.50 per square foot

Step 1. Calculate the Base Area

Formula:

• Base Area = Length × Width

Calculation:

• Base Area = 30 ft x 20 ft
• Base Area = 600 sq ft

Step 2. Calculate the Pitch Percentage

Formula:

• Pitch (%) = (x / 12) x 100

Calculation:

• • Pitch (%) = (4 / 12) x 100
  • Pitch (%) = 0.33 x 100

• Pitch (%) ≈ 33.33%

Step 3. Calculate the Pitch in Degrees

Formula:

• Pitch (deg) = arctan (Pitch Ratio)

Calculation:

• Pitch (deg) = arctan (4 / 12)

• Pitch (deg) = arctan (0.3333)
• Pitch (deg) ≈ 18.43°

Step 4. Calculate the Roof Area

Formula:

• Roof Area = Base Area / cos [Pitch (deg)]

Calculation:

First, find the cosine of the pitch degree:

• cos [Pitch (deg)]
• cos (18.43°) ≈ 0.949

Now, add the values into the equation:

• • Roof Area = 600 sq ft / 0.949

• Roof Area ≈ 632.75 sq ft

Step 5. Calculate the Roofing Cost

Formula:

• Roofing Cost = Unit Price x Roof Area

Calculation:

• Roofing Cost = $3.50per sq ft x 632.75 sq ft
• Roofing Cost ≈ $2,214.63

Standard Roof Pitch Area Multipliers:

Relevant FAQs!

What if my roof is irregularly shaped?

If your roof is an irregular shape, break it down into smaller and regular sections. After that calculate each of the sections separately, and then sum up the totals.

How much does it cost to roof a 1500-square-foot house?

Let’s have a look at this table to get a clear idea!