How do I convert a roof pitch given as a ratio to degrees?

Divide the rise by the run to get the slope fraction, then take the arctangent of that value. For example, a 6:12 pitch becomes 6 ÷ 12 = 0.5, and arctan(0.5) ≈ 26.57°.

What is roof pitch percentage and how is it calculated?

Roof pitch percentage is the vertical rise expressed as a percentage of the horizontal run. Multiply the rise-run ratio by 100; so a 6:12 pitch is (6 ÷ 12) × 100 = 50%.

Do I need to know the total roof span to use these calculators?

Not necessarily. Most tools ask for rise and run (the vertical height and horizontal distance), which are enough to determine the slope angle and rafter length. Total span is only needed if you are calculating overall roof area.

Can I use these tools with metric measurements?

Yes. Number Convert and Omni Calculator both accept metric inputs for rise and run, and will output the pitch in degrees, percent, or ratio regardless of the unit system you start with.

Why does one calculator show a surface multiplier while another does not?

The surface multiplier is the factor by which the flat footprint area is increased to get the actual sloped roof area. It comes from the Pythagorean theorem applied to the rise and run; tools that include it help estimate shingle or metal panel quantities more accurately.

Construction3 options compared

Roof Pitch Calculator

Contractors, architects, and DIY homeowners use the Roof Pitch Calculator to determine the exact slope and dimensions of a roofing structure. By inputting common measurements like the rise and run or the total span of a building, users can instantly calculate the roof pitch in degrees and percentages. This functionality simplifies the complex geometry required for planning new construction or...

Roofing calculators

Editors’ Top PickBased on community votes

Number Convert

numberconvert.com

Convert roof pitch between ratio, degrees, and percentage

Open Number Convert Read review →

Other OptionsRanked by votes

02
02
Omni Calculator
omnicalculator.com
The roof pitch calculator finds the length of the rafter and the roof slope (in degrees and in percent).
Open site View details
03
03
GQ Calc
gqcalc.com
Use this roof pitch calculator to convert rise and run into an x-in-12 pitch, roof angle, slope percentage, and roof-...
Open site View details

Side by side

Roof Pitch Calculator options compared

Tool	Best for	Strengths	Limitations
Omni Calculator omnicalculator.com	Finding rafter length and slope	Calculates rafter length Gives pitch in degrees and percent Simple run and rise inputs	Fewer unit options Basic interface
Number Convert numberconvert.com	Converting between pitch formats	Converts ratio, degrees, and percentage Immediate three-way conversion Works from blueprints or specs	No rafter length calculation Ads on the page
GQ Calc gqcalc.com	Surface multiplier and x:12 pitch	Shows roof-surface multiplier Normalizes to x:12 pitch Includes angle and percent slope	Does not select code-compliant pitch Limited to rise/run input only

Buyer's guide

How to choose a roof pitch calculator

When picking a roof pitch calculator, the key decision is whether you need just the slope angle or full dimensional data. If you are ordering materials or cutting rafters, you need rafter length — that makes Omni Calculator the practical choice. If you are comparing plans, converting blueprint notes, or working with existing slope data, Number Convert handles the format translation without requiring you to input rise and run separately.

Questions

Roof Pitch Calculator FAQ

How do I convert a roof pitch given as a ratio to degrees?: Divide the rise by the run to get the slope fraction, then take the arctangent of that value. For example, a 6:12 pitch becomes 6 ÷ 12 = 0.5, and arctan(0.5) ≈ 26.57°.
What is roof pitch percentage and how is it calculated?: Roof pitch percentage is the vertical rise expressed as a percentage of the horizontal run. Multiply the rise-run ratio by 100; so a 6:12 pitch is (6 ÷ 12) × 100 = 50%.
Do I need to know the total roof span to use these calculators?: Not necessarily. Most tools ask for rise and run (the vertical height and horizontal distance), which are enough to determine the slope angle and rafter length. Total span is only needed if you are calculating overall roof area.
Can I use these tools with metric measurements?: Yes. Number Convert and Omni Calculator both accept metric inputs for rise and run, and will output the pitch in degrees, percent, or ratio regardless of the unit system you start with.
Why does one calculator show a surface multiplier while another does not?: The surface multiplier is the factor by which the flat footprint area is increased to get the actual sloped roof area. It comes from the Pythagorean theorem applied to the rise and run; tools that include it help estimate shingle or metal panel quantities more accurately.

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