A Quick Guide to Roof Measurements

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A Quick Guide to Roof Measurements

A Quick Guide to Roof Measurements

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Before starting any roofing project, contractors will typically need the total square footage of the roof they’ll be working on.

This will not only help them determine strategies, processes, and estimates for the roofing materials needed, but it will also save time once their team is at the job site.

For homeowners, taking these measurements might seem daunting, but it’s definitely doable with some hard work and patience. In this complete guide, we’ll share how to measure your roof right!

When Do You Need to Measure a Roof?

Any major roofing project will need accurate measurements so you know HOW MUCH MATERIAL to buy.

While you can certainly make a rough guess, purchasing too many materials will cost you extra, which might cause you to go over your budget.

With that said, to avoid extra expenses and project delays while re-roofing your house, make sure to measure your roof properly!

Tools Needed for Accurate Roof Measurements

Measuring roofs isn’t easy, so it’s best to have handy tools on hand to help you out! Here are some of the basic materials you’ll need to measure roofing:

Before going up to your roof, MAKE SURE to wear safety equipment, especially if you aren’t a seasoned roofer. After all, even professionals are required to wear these when working at great heights!

Roof Measurement Steps

Before you start, know this whole process is time-consuming, so it’s a good idea to free up a big part of your day to achieve accuracy while doing the task! Here’s how to measure your roof:

Step One: Determine the Roof Type

First, determine the layout of your roof.

Are you working with a hip roof, a gable roof, a Mansard roof, a flat roof, or a different style altogether?

Each type will require different calculations to get the square footage, so it’s important to get a sense of the shape of the roof.

Draw a rough sketch on a piece of paper so you have a guide you can label while taking linear measurements.

While doing this, make sure to include any extra components on the roof (like chimneys, dormers, skylights, etc.) so you can subtract them from the square footage that you’ll calculate later on.

Step Two: Measure the Roof

Next, go up to your roof and measure all sides!

If you’re working with mainly square and rectangular shapes, you’ll have to get the length and width to compute for square footage, but it’s slightly more complicated for irregular shapes.

The trick with these is to cut them up into simpler shapes like a square, rectangle, and/or triangle, so you can simply add up the areas later on to get square footage.

Every time you take measurements, write them down so that you don’t have to repeat the process if ever you forget the values!

Step Three: Determine the Roof Pitch or Slope

Once that’s done, you now have to determine the roof pitch.

The slope of a roof is very important, as it facilitates the proper flow of water and debris away from your house.

The pitch DETERMINES which roofing materials are most suitable and durable for your home.

For example…

  • Asphalt shingles can only be installed on roofing that has a minimum roof slope of 2:12, while slate shingles require a pitch of at least 4:12.
  • Any lower and rainwater will probably pool up on your roof/between the shingles, creating a big mess (and an even bigger problem for you later on!)




This figure will vary among different types of roofs, so remember your observations in step one.

For example, hip roofs typically have steep slopes, while Mansard roofs have a combination of steep and low slopes.

To get this ratio, simply measure the vertical height (rise) over a horizontal 12-inch length (run).

Step Four: Calculate the Square Footage of the Roof

It’s time to add up all your figures in step two to get the square footage!

  1. Get the area of each square, rectangle, and triangle you drew out.
  2. Then, get the sum.
  3. For a more accurate measure, multiply this by the slope or pitch factor.
  4. Ideally, you should subtract the areas of the roof that don’t need roofing material as well.

If this is a little too complicated for you, though, you can always hire a professional contractor to help you out.

Step Five: Estimate the Amount of Roofing Materials Needed to Cover the Total Area

Now you have all the measurements, all that’s left is to estimate how much roofing material you actually need to cover your entire roof.

  1. First, check which sizes and quantities your preferred roofing materials are sold in. For example, shingles are usually sold in bundles, tiles are sold per piece, while metal roofing is sold by sheets.
  2. Determine the square footage a bundle, piece, or sheet will cover, then divide your total roof area (from step four) by this number.
  3. Now you have the exact quantity of roofing material you need for your property!

Pro roofing tip: To be safe, we recommend buying a little extra roofing material just in case your measurements are a bit off. Don’t worry, it won’t cost too much!

Tips to Get Precise Measurements

Before you go, here are some bonus tips to help you measure your roof as professional contractors do!

  • Have an organized system/process before starting the project. Lay out all the tools you need, and familiarize yourself with the steps so you know exactly what to do once you’re up on the roof.
  • While measuring roofing, always use a level to make sure you’re going in a straight line. Otherwise, your measurements for square footage and slope will be off.
  • Account for structures that need additional roofing material such as ridges and valleys. Subtract areas that don’t need it (like chimneys and pipes).


Most homeowners don’t realize they can get their roof’s square footage by themselves.

Whether you’re dealing with a hip roof, a gable roof, or any other kind of roof, all you have to do is follow these steps to get a good estimate of your roof’s measurements!

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