Question 1

What is roof pitch?

Accepted Answer

Roof pitch describes the steepness of a roof. It is typically expressed as a ratio in the format X:12, meaning the roof rises X inches for every 12 inches of horizontal distance (run). For example, a 6:12 pitch means the roof rises 6 inches for every 12 inches of horizontal run. Pitch can also be expressed as an angle in degrees or as a slope percentage.

Question 2

How do you calculate roof pitch?

Accepted Answer

Roof pitch = Rise divided by Run, multiplied by 12. For example, if the rise is 6 feet and the run is 12 feet, the pitch is (6/12) x 12 = 6:12. The angle is calculated as arctan(Rise/Run), the slope percentage is (Rise/Run) x 100, and the rafter length is the square root of (Rise squared + Run squared).

Question 3

What are common roof pitches?

Accepted Answer

Flat roofs: 0 to 1:12. Low slope: 1:12 to 3:12. Conventional slope: 4:12 to 9:12. Steep slope: 10:12 to 12:12. High slope: above 12:12. Most residential homes use a pitch between 4:12 and 9:12.

Question 4

How do I calculate rafter length from roof pitch?

Accepted Answer

Rafter length is calculated using the Pythagorean theorem: rafter = square root of (rise squared + run squared). This gives you the length of the sloped side of the roof from the ridge to the wall plate.

Question 5

Can this calculator estimate roof surface area?

Accepted Answer

Yes. Enter your roof footprint area (the flat projection seen from above), and the calculator multiplies it by the roof area multiplier, which is the square root of (1 + (rise/run) squared). This accounts for the extra surface area created by the roof's slope.

🏠 Roof Pitch Calculator

📐 Input Parameters

📊 Results

🏠 Roof Diagram

📐 Roof Surface Area Calculator