What roof pitch is and why it matters
Roof pitch is the angle or steepness of your roof, expressed as a ratio of rise to run. A pitch of 6:12 means the roof rises 6 inches for every 12 inches of horizontal distance. Pitch matters because it affects how water drains, how much snow and ice accumulate, what materials you can use, and how difficult repairs or replacement will be.
You need to know your roof pitch before buying shingles, planning repairs, or hiring a contractor. Different materials work on different pitches — some asphalt shingles require a minimum pitch of 4:12, while metal roofing can work on pitches as low as 3:12. Contractors also price jobs differently based on pitch because steeper roofs are harder and more dangerous to work on.
Key Takeaways
- Roof pitch is the ratio of vertical rise to horizontal run, written as rise:run (for example, 6:12 means 6 inches up for every 12 inches across).
- You can find pitch by measuring directly on the roof with a level and tape measure, or by checking your home's original blueprints or permit documents.
- A pitch angle finder or smartphone app can give you a quick measurement if you can safely access the roof edge.
- If you cannot safely measure yourself, a roofer or home inspector can determine pitch in minutes as part of an inspection.
Measuring pitch with a level and tape measure
This is the most common method and requires only two tools: a straight level (at least 2 feet long) and a tape measure. You will need safe access to the roof — either from a ladder against the edge or from inside an attic where you can see the roof framing.
Place the level horizontally against the underside of a rafter or against the roof surface itself. Measure straight up from the end of the level to the roof surface above it. That vertical distance, compared to the 12-inch (or 24-inch, depending on your level length) horizontal span of the level, gives you your pitch. For example, if your level is 24 inches long and the vertical distance is 12 inches, your pitch is 12:24, which simplifies to 6:12.
Take measurements in at least two or three spots on different parts of the roof, because pitch can vary slightly across a complex roof with multiple sections. If the measurements differ, note which sections have which pitches — this matters if you are replacing only part of the roof.
Using a pitch angle finder or smartphone app
A pitch angle finder (also called a roof pitch gauge or inclinometer) is a handheld tool that reads the angle directly. You place it flat against the roof surface and it shows the pitch as both an angle in degrees and as a ratio. These tools cost between $15 and $50 and are accurate to within a degree or two.
Smartphone apps that use your phone's built-in inclinometer can also measure pitch, though they are less reliable than a physical tool because the phone must be placed perfectly flat. If you use an app, take multiple readings and average them. Both methods work only if you can safely reach the roof edge or a sloped surface — do not climb onto a roof if you are not comfortable doing so.
Finding pitch from blueprints and permits
Your home's original blueprints or building permit documents often list the roof pitch. These are usually stored with your home's deed or closing documents, or you can request them from your city or county building department. The permit process typically includes a site plan or elevation drawing that shows the pitch.
Call your local building department and ask for the permit file for your address. Many departments now allow you to search online. If your home was built more than 20 or 30 years ago, the records may be in storage and take a few days to retrieve, but the cost is usually under $25.
Asking a professional to measure
If you cannot safely access your roof or prefer not to measure yourself, a roofer or home inspector can determine pitch in minutes. Many roofers will measure pitch for free as part of an initial inspection or quote. Home inspectors measure pitch as part of a full inspection, which typically costs $300 to $500 depending on your home's size and location.
If you are already planning to have work done — repairs, replacement, or an inspection — ask the contractor to document the pitch in their report. This gives you a record for future reference and for any future contractors you hire.
Understanding pitch notation and conversion
Pitch is written as rise:run, almost always with the run as 12. A pitch of 6:12 is read as "six in twelve" and means 6 inches of rise for every 12 inches of horizontal run. Common residential pitches range from 4:12 (a gentle slope) to 12:12 (a 45-degree angle) to 16:12 (a steep pitch).
Pitch can also be expressed as an angle in degrees. A 6:12 pitch equals roughly 26.5 degrees. If a contractor or material specification gives you an angle instead of a ratio, you can convert it: divide the rise by 12, then use a calculator to find the inverse tangent (arctan) of that number. For most common pitches, a quick online converter is faster and more accurate than doing the math by hand.
What to do if your roof has multiple pitches
Many homes have roofs with different pitches on different sections — a main roof at one pitch and a porch or addition at another. Measure each section separately and note which is which. If you are replacing the entire roof, you will need to order materials for each pitch. If you are replacing only one section, knowing the exact pitch of that section prevents you from ordering the wrong materials.
When you get quotes from roofers, tell them about the multiple pitches and ask them to break down the cost by section. This helps you understand what you are paying for and makes it easier to compare quotes from different contractors.
Frequently Asked Questions
Can I estimate pitch just by looking at my roof?
Not accurately. A roof that looks steep to one person may look moderate to another, and the difference between a 6:12 and an 8:12 pitch is real but hard to judge by eye. Always measure or use a tool. Guessing can lead you to order the wrong materials or get an inaccurate contractor quote.
What if I cannot safely get to my roof to measure?
Do not climb onto a roof if you are uncomfortable or unsafe doing so. Call a roofer or home inspector instead. The cost of a professional measurement is far less than the cost of a fall or injury. Many roofers measure pitch for free as part of an initial consultation.
Does pitch affect how much a new roof costs?
Yes. Steeper roofs cost more to replace because they are harder and more dangerous to work on. A 4:12 pitch roof will cost less to replace than a 12:12 pitch roof of the same size. Pitch also affects material choices — some shingles and coatings have minimum pitch requirements.
If I know the angle in degrees, how do I convert it to a ratio?
Multiply the tangent of the angle by 12. For example, a 26.5-degree angle: tan(26.5°) × 12 ≈ 6, so the pitch is 6:12. An online roof pitch converter is faster and more reliable than doing this by hand.
Why do contractors sometimes give different pitch measurements?
Pitch can vary slightly across different sections of a roof, especially on older homes or homes with additions. Always ask contractors to measure multiple spots and note any variations. If two contractors give very different measurements, ask them to show you where they measured.