Roof Pitch Calculator
Enter any rise and run you measured, in inches. The calculator converts it to the standard "x in 12" pitch and gives you the angle and the multipliers you need for ordering material.
Find your roof pitch
Have an angle instead? Convert degrees to pitch
What roof pitch means
Roof pitch is how many inches a roof rises for every 12 inches it runs horizontally. A 6/12 roof ("six in twelve") climbs 6 inches over each foot of level distance. Builders and suppliers in the US use this ratio instead of degrees because it can be checked with a tape measure and a level, and because the numbers plug straight into framing and material math.
You do not need to measure a full 12 inches. Any rise and run give the same pitch once you scale the run to 12, which is what the calculator does. That is handy when the only flat spot you can reach is a short section of rafter.
Formulas
The pitch multiplier converts flat (plan) area or horizontal run into true sloped length or area. The hip/valley factor does the same job for hip and valley lines on a roof where both planes have the same pitch, measured per foot of common-rafter run.
Worked examples
Common pitches at a glance
| Pitch | Angle | Multiplier | Slope % | Hip/valley factor |
|---|---|---|---|---|
| 1/12 | 4.76° | 1.0035 | 8.3% | 1.4167 |
| 2/12 | 9.46° | 1.0138 | 16.7% | 1.4240 |
| 3/12 | 14.04° | 1.0308 | 25.0% | 1.4361 |
| 4/12 | 18.43° | 1.0541 | 33.3% | 1.4530 |
| 5/12 | 22.62° | 1.0833 | 41.7% | 1.4743 |
| 6/12 | 26.57° | 1.1180 | 50.0% | 1.5000 |
| 7/12 | 30.26° | 1.1577 | 58.3% | 1.5298 |
| 8/12 | 33.69° | 1.2019 | 66.7% | 1.5635 |
| 9/12 | 36.87° | 1.2500 | 75.0% | 1.6008 |
| 10/12 | 39.81° | 1.3017 | 83.3% | 1.6415 |
| 11/12 | 42.51° | 1.3566 | 91.7% | 1.6853 |
| 12/12 | 45.00° | 1.4142 | 100.0% | 1.7321 |
Need steeper pitches? The pitch to degrees chart runs to 24/12. Each common pitch also has its own page with framing and area numbers: 1/12 · 2/12 · 3/12 · 4/12 · 5/12 · 6/12 · 7/12 · 8/12 · 9/12 · 10/12 · 11/12 · 12/12.
How pitch changes the job
- Material. Standard asphalt shingle installs need at least 4/12; between 2/12 and 4/12 most codes require extra underlayment. Below 2/12, use a low-slope membrane. See roof pitch examples for what works where.
- Area. Steeper roofs have more surface over the same footprint. Use add for pitch to see exactly how much.
- Labor and safety. Many crews treat anything above about 7/12 as steep work that needs roof jacks or harnesses, and charge more for it.
Frequently asked questions
How do I calculate roof pitch?
Measure the rise (vertical) and run (level) in the same units, then divide rise by run and multiply by 12. A 5-inch rise over 10 inches of run is 12 × 5 ÷ 10 = 6, so the pitch is 6/12.
What is the most common roof pitch?
On US houses, pitches from 4/12 to 9/12 are the most common. 6/12 is a typical middle value: walkable for most roofers and steep enough to shed water well with shingles.
Is roof pitch the same as roof slope?
People use the words loosely. Strictly, pitch was once rise divided by the full span, while slope is rise per 12 of run. Today almost everyone means rise per 12 inches of run when they say pitch, and that is what this calculator reports.
How many degrees is a 6/12 pitch?
A 6/12 pitch is 26.57 degrees. Use the degree converter above or the full chart for other pitches.
What is a pitch multiplier used for?
Multiply a flat footprint area, or a horizontal run, by the pitch multiplier to get the true sloped area or rafter length. For 6/12 the multiplier is 1.118, so a 1,500 sq ft footprint has about 1,677 sq ft of roof.
Last reviewed 2026-10-10. Results are estimates for planning; confirm quantities with your supplier and requirements with your local building code and the manufacturer's instructions.