Roofing Calculator Guide

Blog August 3, 2020

A good roof size calculator and roofing material calculator are indispensable tools whenever you’re working on any roofing project. Both give you an idea on the amount and cost of the material you need to buy based on your roof’s area.

However, to get the best results from your roof area calculator, you need to start with accurate measurements. Correctly measuring the different areas of your roof is vital, as even the best roof square footage calculator will not do this for you.

Don’t know where to start? Here’s how to measure your roof for use with your roofing calculator.

How to measure for area

Any roofing calculator starts by giving a reasonably accurate estimate of the total area of your roof. If you remember high school geometry, area is simply the measurement (often in square feet) of the space occupied by a flat surface.

The simplest method of calculating your roofing square footage is by measuring the base width and length of your roof. To start, get the distance from one corner of your roof to the other on your house’s shorter side. This will be your base width. To figure out your base length, measure from one corner to the other on your house’s longer side.

For flat roofing, this method works reasonably well. However, for most roofs with height, you need to account for the slope or pitch, as this will impact the results of a roof size calculator. We’ll discuss how to account for that in a later section.

Measuring for materials

If you’re fixing your roof yourself, knowing the area is only practical if it will also tell you how much material you’ll actually need. Fortunately, most calculators provide this information.

Estimating the number of shingles you need for your roof is one of the primary considerations of any builder. A roof shingle calculator tells you how many bundles of shingles you’ll need for a given area. One standard bundle often covers around 33 square feet worth of roofing. Any decent shingle calculator will also add a buffer to account for trimming waste, which is around 10% for a standard roof and 15% for roofing with hips and valleys.

Calculators also estimate other materials you need for your roofing project, such as roll roofing and felt rolls.

How roof pitch is calculated

As we mentioned before, relying only on the base width and length of your roof isn’t going to give you accurate results. That’s why any decent roofing square calculator will require you to include the pitch of the roof as well.

Pitch, or slope, is a measure of how much a roof rises compared to how it runs horizontally. Essentially, it tells you how steep or flat a roof is.

Pitch is denoted with an “X in Y” convention, where X is the vertical rise of the roof, and Y is horizontal. For example, a pitch of “12 in 12” means there’s a 12-foot height increase for every 12 foot worth of roofing. Visually, a 12 in 12 pitch is a very steep roof slanted at a 45-degree angle.

How to measure for roof pitch

Luckily, you don’t need to measure your entire roof to figure out its pitch. You can measure just a portion of it using a simple method. All you need is a level, and either a ruler or a tape measure.

First, climb a ladder and align the level horizontally over your roof, with the 0” mark touching the edge of the roof. Then, using a ruler, measure the vertical distance from the level’s 12” mark down to the surface of the roof, forming a triangle. Whatever the result will be the vertical rise of the roof. So for example, if you get 5”, then you have a 5 in 12 pitch.

Alternatively, you can measure the pitch from your attic if you prefer to do it indoors. The principle is the same. Put the level against a portion of the attic’s rafter horizontally, then measure from the 12” mark vertically until it reaches another part of the rafter. That distance is your pitch.

Tips on measuring for roofing

Measuring your roof’s dimensions is one of the most important aspects of any roofing job, so make sure your tools are up to par. An accurate ruler, tape measure, and a sturdy ladder are all required.

The problem is that not everyone is comfortable with climbing a ladder to do this. What’s more, there is no guarantee that the measurements will be correct. That error can cost you more money, time, and effort.

That’s why it’s best just to hire or consult a professional roofing contractor. They will have the tools, knowledge, and experience to help you accurately measure your roof and figure out how much materials you need with minimal waste.

Working with JAE Construction

Are you living in South Florida and need someone to help you size your roof up? The Fort Lauderdale roofing experts at JAE Construction use the latest satellite technology to precisely measure your roof. We won’t even take time out of your precious day. Contact us today and get a free quote!