Roof Pitch Calculator

Roof pitch is the slope or steepness of a roof, typically expressed as a ratio like 4:12, meaning the roof rises 4 units for every 12 units of horizontal run. It can also be expressed as an angle in degrees or as a percentage.

To calculate roof pitch, divide the rise by the run. For example, if your roof rises 4 feet over a 12-foot run, the pitch is 4/12 or 1/3. This is commonly written as 4:12 pitch.

The most common roof pitches range from 4:12 to 9:12. A 6:12 pitch (26.57° angle) is considered standard for many residential homes as it provides good water drainage while being practical to build and maintain.

A 4/12 roof pitch means the roof rises 4 units vertically for every 12 units horizontally. This creates an angle of approximately 18.43 degrees and is considered a moderate slope that's suitable for most roofing materials.

For areas with heavy snow loads, a minimum pitch of 6:12 (26.57°) is recommended to ensure proper snow shedding. Steeper pitches like 8:12 or 9:12 are even better for preventing snow accumulation.

The best roof pitch depends on your climate, roofing material, and architectural style. Generally, 6:12 to 8:12 pitches work well for most situations, providing good drainage, snow shedding, and structural efficiency.

Rafter length is calculated using the Pythagorean theorem: rafter² = rise² + run². Take the square root of the sum to get the rafter length. Don't forget to add any overhang length to the total.

Pitch is typically expressed as a ratio (like 4:12), while slope can be expressed as a percentage, decimal, or angle. Both describe the steepness of the roof but use different units of measurement.