Roof Pitch Chart: Know Your Roof Slope Before You Build
Stop guessing your roof slope. Explore common pitch ratios, angles, and measurements in one easy-to-use Roof Pitch Chart.
Step 1
Set your pitch
26.6°
Angle
50%
Slope
1.12×
Multiplier
Step 2
Roof footprint & waste
Footprint = the flat, bird's-eye area your roof covers (not the sloped surface).
Roof Pitch Chart: What Does 4/12, 6/12, or 8/12 Mean?
Taemin Kim
Creator & Construction Expert
"I keep seeing these fraction numbers on build plans. What do they actually mean?"
Here's the deal: a roof pitch fraction tells you how many inches a roof rises vertically for every 12 inches it extends horizontally.
- 4/12 Pitch: Rises 4 inches for every 12 inches of horizontal run.
- 6/12 Pitch: Rises 6 inches for every 12 inches of horizontal run.
- 8/12 Pitch: Rises 8 inches for every 12 inches of horizontal run.
Using a standard roof pitch chart removes guessing when buying shingle bundles, planning attic storage, or ordering exterior siding.
How to Read a Roof Pitch in Seconds
"Which number is the rise, and which one is the run?"
Look at any pitch ratio as two distinct measurements:
- The First Number (Rise): Tells you the vertical height change in inches.
- The Second Number (Run): Stays locked at 12 inches across standard building plans.
Understanding how to read roof pitch means you instantly know how steep a roof feels before stepping foot on a ladder. Having roof pitch explained simply comes down to one rule: the higher the first number, the steeper the roof.
Common Roof Pitches Compared
"Is 6/12 steep? How does it compare with 4/12 or 8/12?"
Roof slope dictates what roofing materials you can install, how fast rainwater drains, and whether workers need safety harnesses during installation.
Comparing common roof pitches side by side:
| Pitch Ratio | Steepness Category | Walkability & Material Fit |
|---|---|---|
| 1/12 to 3/12 | Low Slope / Flat | Barely sloped. Requires rubber membrane or standing seam metal. |
| 4/12 to 6/12 | Conventional / Moderate | Easy to walk on. Fits standard asphalt shingles perfectly. |
| 7/12 to 9/12 | Steep Slope | Hard to walk on. Fast water runoff; requires harness safety gear. |
| 10/12 to 12/12+ | Very Steep / A-Frame | Dangerously steep. Eye-catching look; snow slides off instantly. |
A direct roof pitch comparison shows why a 6/12 slope sits in the sweet spot for standard residential home builds—it sheds heavy rain and snow without driving up labor costs.
Roof Pitch, Degrees, and Angle: How Do They Compare?
"I have the pitch ratio, but my solar panel layout or truss order asks for the angle in degrees."
Building suppliers list slope as a fraction, but solar installers and truss manufacturers ask for degrees. Converting pitch ratios into true angles requires a simple trigonometric calculation:
Use this reference roof pitch to degrees conversion table:
| Pitch Ratio | Angle in Degrees |
|---|---|
| 2/12 | 9.5° |
| 4/12 | 18.4° |
| 6/12 | 26.6° |
| 8/12 | 33.7° |
| 10/12 | 39.8° |
| 12/12 | 45.0° |
Bookmark this roof pitch angle chart so your solar mounts, framing cuts, and rafter tails line up without expensive job-site rework.
Find Your Roof Pitch From a Simple Measurement
"I don't know my roof slope. How can I work it out myself?"
You don't need to climb high onto a slippery roof to figure out your slope. You can measure it safely from inside your attic along a bare rafter board.
Follow these three steps on how to calculate roof pitch:
- Place a 12-inch bubble level flat against the bottom edge of an exposed roof rafter.
- Measure straight up vertically from the 12-inch mark on the level to the rafter bottom.
- That vertical inch count is your rise number. If it measures 6 inches up, your roof is a 6/12 pitch.
Want to skip manual attic math entirely? Plug your rafter height and run numbers into our free roof slope calculator on DesignHome to get instant slope ratios, angles, and material estimates for your property project.
Planning a home build or replacing an aging roof? Explore exterior house styles in our guide on contemporary house layouts or review interior structural spacing in our breakdown of multi-room layout options.
Continue Planning Your Project
Frequently Asked Questions
What is the most common roof pitch for residential homes?
Most standard homes use a 4/12 to 6/12 pitch. This range drains rainwater quickly, holds asphalt shingles securely, and lets roofers walk on the surface without specialized safety harness rigs.
How do you convert roof pitch to degrees?
Divide your rise by 12, then calculate the inverse tangent (arctan). For example, a 6/12 pitch gives arctan(6/12) = 26.6°. You can also check a roof pitch chart to convert ratios to angles instantly.
Is a 4/12 roof pitch safe to walk on?
Yes. A 4/12 roof rises only 4 inches for every 12 inches of horizontal run, making it a comfortable, low-risk slope for basic home repairs, gutter cleanouts, and shingle installs.
What is the lowest roof pitch allowed for asphalt shingles?
The absolute minimum is 2/12, but any slope between 2/12 and 4/12 requires a double layer of waterproof underlayment to prevent wind-driven rain from backing up under shingles. For standard single-layer underlayment, stick to 4/12 or higher.
How do I measure my roof pitch from inside the attic?
Hold a 12-inch bubble level flat against the bottom edge of a bare rafter board. Measure straight up vertically from the 12-inch mark on the level to the rafter. That vertical inch reading gives you your rise ratio over 12.
What does a 12/12 roof pitch mean?
A 12/12 pitch rises 12 inches for every 12 inches of horizontal distance, forming a steep 45.0° angle. Snow slides off immediately, but workers cannot walk on it without full harness safety gear.
Why does a steeper roof pitch increase replacement costs?
Steep roofs (7/12 and higher) expand your total surface square footage compared to your home's ground footprint. They also require slow, careful staging, scaffolding, and harness rigs, which increases labor time and material costs.
What roof pitch works best for solar panel installation?
Pitches between 6/12 (26.6°) and 8/12 (33.7°) sit in the ideal position for solar panels, capturing maximum sun exposure without requiring angled mounting brackets.
How does pitch affect water drainage during heavy storms?
Low pitches (1/12 to 3/12) hold standing water longer and require seamless rubber or metal roofing. Steeper slopes (6/12 and up) shed rainwater and melting snow immediately, protecting against roof leaks.
Where can I calculate my roof pitch and material needs without doing math?
You can run your rafter height, run distance, and house footprint through our interactive roof slope calculator on DesignHome to get instant angles, pitch ratios, and shingle estimates.