Roof Pitch Calculator
Calculate roof pitch, roof slope, pitch angle, rafter length, roof surface area, roofing squares, and an estimated roofing cost from your roof measurements.
Calculate roof pitch
Enter the rise and horizontal run of your roof. You can also enter the building dimensions to estimate roof area and roofing cost.
26.57° roof angle
A 6/12 roof rises 6 inches for every 12 inches of horizontal run.
How to use the roof pitch calculator
This roof pitch calculator helps you determine the pitch, slope, and angle of a roof from two simple measurements: the vertical rise and the horizontal run.
If you also enter your building length and width, the calculator can estimate the roof surface area, roofing squares, material waste, and an approximate roofing cost.
- Measure the vertical rise of the roof.
- Measure the horizontal run.
- Enter both measurements into the calculator.
- Review the roof pitch and angle.
- Optionally enter the building length and width.
- Enter a local roofing cost per square foot.
- Click Calculate roof pitch.
What is roof pitch?
Roof pitch describes how steep a roof is. In the United States, roof pitch is commonly expressed as the amount of vertical rise for every 12 inches of horizontal run.
For example, a 6/12 roof pitch means the roof rises 6 inches for every 12 inches of horizontal run. A 4/12 roof rises 4 inches for every 12 inches of run, while an 8/12 roof rises 8 inches.
Roof pitch can also be expressed as a slope or as an angle in degrees. The calculator converts between these measurements automatically.
How to calculate roof pitch
To calculate roof pitch, divide the vertical rise by the horizontal run.
To express the result as a standard roof pitch, use a 12-inch run. For example, if a roof rises 6 inches over a 12-inch horizontal run, the roof pitch is 6/12.
If your measurements are not based on a 12-inch run, the calculator converts the slope into the standard X/12 roof pitch format.
How do you calculate the pitch of a roof?
Measure the vertical rise and horizontal run of the same section of roof. Divide the rise by the run to determine the slope. You can then convert the slope to a roof pitch expressed as X/12.
For example, suppose a roof rises 8 inches over a 16-inch horizontal run.
- Rise = 8 inches
- Run = 16 inches
- Slope = 8 ÷ 16 = 0.50
- Equivalent roof pitch = 6/12
- Roof angle = about 26.57°
Roof pitch to degrees
Roof pitch can be converted to an angle using the arctangent of the roof slope.
For example, a 6/12 roof has a slope of 0.50. The corresponding roof angle is approximately 26.57 degrees.
Common roof pitch angles
The table below shows several common roof pitches and their approximate angles.
| Roof pitch | Rise per 12 in. | Slope | Angle |
|---|---|---|---|
| 2/12 | 2 in. | 0.167 | 9.46° |
| 3/12 | 3 in. | 0.250 | 14.04° |
| 4/12 | 4 in. | 0.333 | 18.43° |
| 5/12 | 5 in. | 0.417 | 22.62° |
| 6/12 | 6 in. | 0.500 | 26.57° |
| 7/12 | 7 in. | 0.583 | 30.26° |
| 8/12 | 8 in. | 0.667 | 33.69° |
| 9/12 | 9 in. | 0.750 | 36.87° |
| 10/12 | 10 in. | 0.833 | 39.81° |
| 12/12 | 12 in. | 1.000 | 45° |
4/12 roof pitch angle
A 4/12 roof pitch rises 4 inches for every 12 inches of horizontal run. Its slope is approximately 0.333 and its roof angle is approximately 18.43 degrees.
6/12 roof pitch angle
A 6/12 roof pitch rises 6 inches for every 12 inches of horizontal run. Its slope is 0.50 and its roof angle is approximately 26.57 degrees.
8/12 roof pitch angle
An 8/12 roof pitch rises 8 inches for every 12 inches of horizontal run. Its slope is approximately 0.667 and its roof angle is approximately 33.69 degrees.
How to calculate roof angle
To calculate the roof angle in degrees, first determine the roof slope by dividing rise by run. Then use the inverse tangent function.
A calculator makes this conversion easier because it automatically converts the measurements into the corresponding angle.
How to calculate rafter length
Rafter length can be calculated using the Pythagorean theorem. For a simple gable roof, the horizontal run and vertical rise form the two shorter sides of a right triangle.
The calculator uses the roof pitch to determine the slope length of one side of the roof.
How roof pitch affects roof area
A sloped roof has more surface area than the horizontal footprint of the building. As roof pitch increases, the sloped roof surface becomes longer.
For a simple gable roof, the calculator uses the building dimensions and the roof slope to estimate the actual sloped roof area. This can then be converted into roofing squares.
One roofing square represents 100 square feet of roof surface. Roofing materials are commonly estimated and sold using this unit.
Roof pitch and roofing cost
Roof pitch can affect the amount of roofing material required because a steeper roof generally has more surface area than the building's horizontal footprint. Steeper roofs can also increase installation difficulty and labor requirements.
Our calculator provides a simple planning estimate based on your estimated roof area and the cost per square foot you enter.
The estimate is not a contractor quote. Actual roofing prices depend on material type, local labor rates, roof complexity, accessibility, tear-off requirements, permits, flashing, ventilation, and other project-specific factors.
Roof pitch calculator example
Suppose a roof rises 6 inches for every 12 inches of horizontal run. The roof pitch is 6/12.
- Rise: 6 inches
- Run: 12 inches
- Roof pitch: 6/12
- Slope: 0.50
- Roof angle: about 26.57°
If the building is 40 feet long and 30 feet wide, the calculator can use the roof slope to estimate the sloped roof surface. Adding a waste percentage provides a more useful material-planning figure.
How much does a new roof cost?
There is no single price for a new roof. Roofing costs vary based on the size and pitch of the roof, roofing material, labor, roof complexity, location, accessibility, and whether the existing roof needs to be removed.
For example, published roofing cost guides show substantial differences between roofing materials and project conditions. Roof pitch is one of the factors that can affect installation cost.
For a quick estimate, enter your expected roofing cost per square foot into this calculator. For a real project, get quotes from local roofing contractors using the actual roof measurements and material specifications.
What is a good roof pitch?
There is no single roof pitch that is appropriate for every building. The appropriate pitch depends on the building design, climate, drainage requirements, roofing material, architectural style, and local building requirements.
Different roofing materials also have different installation requirements. Always check the manufacturer's specifications and applicable building codes before selecting a roof pitch for a new construction project.
How to measure roof pitch
One common method is to measure the rise over a known horizontal run. A level can be used to establish a horizontal reference, while the vertical measurement gives the roof rise.
For example, if the roof rises 6 inches over a 12-inch horizontal distance, the roof has a 6/12 pitch.
If you are measuring an existing roof, work carefully and avoid stepping onto a roof surface unless you have the appropriate equipment, training, and fall protection.
Roof pitch calculator formula
The main formulas used by this calculator are:
Pitch = Slope × 12
Angle = arctan(Slope)
Rafter = √(Run² + Rise²)
Roofing squares = Roof area ÷ 100
Estimated cost = Roof area × Cost per square foot
Frequently asked questions
How do I calculate roof pitch?
Measure the vertical rise and horizontal run, then divide the rise by the run. Convert the result to a 12-inch run to express the roof pitch as X/12.
How do you calculate the pitch of a roof?
Roof pitch is calculated from the relationship between vertical rise and horizontal run. For example, a roof that rises 6 inches over a 12-inch run has a 6/12 pitch.
What is a 6 in 12 roof pitch angle?
A 6/12 roof pitch has a slope of 0.50 and an angle of approximately 26.57 degrees.
What is a 4 in 12 roof pitch angle?
A 4/12 roof pitch has a slope of approximately 0.333 and an angle of approximately 18.43 degrees.
What is an 8 in 12 roof pitch angle?
An 8/12 roof pitch has a slope of approximately 0.667 and an angle of approximately 33.69 degrees.
Can I calculate roof pitch from degrees?
Yes. If you know the roof angle, calculate the slope using the tangent of the angle. The slope can then be converted to the standard X/12 roof pitch format.
How do I calculate roof pitch in degrees?
Divide the roof rise by the horizontal run and take the inverse tangent of the result. The formula is angle = arctan(rise ÷ run).
Does roof pitch affect roofing cost?
It can. Steeper roofs generally have more surface area and may require additional labor, safety equipment, and installation time. Actual pricing depends on the entire roofing project.
How many roofing squares do I need?
Divide the total roof surface area by 100 to convert square feet into roofing squares. Add an appropriate waste allowance when estimating material requirements.
Is the roofing cost estimate accurate?
It is a planning estimate rather than a contractor quote. Actual costs can vary significantly based on roofing material, location, labor, roof complexity, accessibility, tear-off requirements, and other project details.