What is a roof pitch and how do you measure it?

Ana Almerini

By Ana Almerini

January 15, 2021

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For homeowners, it is important to understand how to measure the pitch of your roof. The pitch of a roof, or roof slope, helps determine how quickly excess water, snowfall, or debris will fall off of the roof. The steeper the pitch, the better this will work.

The roof pitch is measured by how much the roof slants upwards. For instance, you could have a completely flat roof with a very low slope or you can have a very steep slope that is almost vertical.

Generally, unless you are remodeling your home, you do not need to worry about what your roof pitch is because the roof is already built according to strict building codes. But we will walk you through how to determine your roof pitch to help when reroofing with new shingles, adding solar panel racking, or redoing the rafters in your attic.

Understanding the roof pitch will help roofing contractors determine how much roofing material to order for certain roof jobs. We will walk you through two ways to simply measure the pitch of your roof. Or for the easiest measurement, use our roof pitch calculator!

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A high pitched roof cabin in the woods and a flat roof home in the desert A high pitched roof cabin in the woods and a flat roof home in the desert

A roof pitch can vary to be extremely steep to essentially flat. Flat roof homes make more sense in climates with less rain and snow since there is less chance of moisture pooling up on the roof. Image sources: Dezeen & Home Edit

How to determine your roof pitch from the roof

The easiest way to measure your roof pitch is to use our roof pitch calculator by inputting the measurements from your home. Or, if you want to measure the roof surface yourself, you can think back to algebra class when you learned how to measure a slope as rise over run, the slope is now your roof.

A gable roof style is one of the easiest roofs to measure since it is generally a low pitch that is even throughout the entire house. If you are not a contractor and do not need exact measurements down to the millimeter and degree angle, there is a simple way to measure your roof if you have access to it.

What you need:

  • A tape measure
  • A spirit level
  • A ladder and the ability to safely sit on your roof

How to calculate your roof slope

Measuring your roof pitch is as simple as using the rise over run equation, the rise being the vertical component and the run being horizontal. For every foot (or run) that your roof extends horizontally, it rises by "x" amount of inches. To determine the "x", you can use a simple measuring technique.

  1. After safely accessing your roof, measure 1-foot up from the base of the roof using your measuring tape, this will give you the horizontal run.
  2. Place the end of the level at the 1-foot mark but make sure it is creating an "L" shape. Meaning, one of the bottom corners of the level touches the roof but the other bottom corner is suspended in the air.
  3. Once the bubble of air in the level is in the middle, measure from the bottom of the level to the top of the roof. This will give you the vertical rise.

For example, if what you measured for the "rise" is 6 inches, then the roof pitch is 6/12, meaning for every 12 inches of horizontal length of the roof, the roof rises 6 inches. Steeper pitches will have a higher rise number, say 10/12, versus lower pitched roofs which can be as low as 2/12 for roofs with asphalt shingles, but can be even lower for metal roofs or gambrel style homes with roofs that have many different shaped pitches.

How to calculate roof pitch

How to measure your roof pitch from inside the attic

If you cannot access your roof or do not feel comfortable doing so, you can safely measure your roof pitch using the truss structures within your attic by measuring the rafter length.

  1. Measure 1-foot from the base of the roof on the attic floor, which is the horizontal run of 12 inches.
  2. To find the vertical rise, start at the end of the 12-inch mark measurement, simply measure from the floor to the roof rafter.

Using our example measurements from before, say the distance from the floor of your attic to the ceiling is 6 inches, which means your roof pitch is 6/12.

If you have these measurements already, you can input them into our roof pitch calculator to get a more accurate number.

Enter your address to get a quote for your roof

What to do with your roof pitch

Now that you have your roof pitch calculated, you can share this with your roofer so they can determine the amount of materials needed for a new roof, roof repair, or updates that you need to your shingle roof. Measuring the steepness of your roof pitch is rather simple if you have the tools on hand, with just a level and a measuring tape you can quickly determine the “rise over run” of your roof.

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