Roof pitch calculator: pitch, angle and multiplier
Roof pitch is the rise in inches for every 12 inches of horizontal run. Enter any rise and run you measured and this calculator gives the pitch as x/12, the angle in degrees and the multiplier that turns flat footprint into sloped roof area.
On this page
Pitch6/12
- Angle
- 26.6°
- Pitch multiplier
- 1.118
- Slope
- Walkable for most crews
Runs in your browser. Nothing you type is sent or saved. The result is an estimate from your own inputs, not a quote.
How to measure roof pitch
- Hold a level flat. In the attic against a rafter, or on the roof surface, hold a level so the bubble is centered.
- Mark 12 inches along the level. That is the run.
- Measure straight down from that mark to the roof. That is the rise. Six inches means a 6/12 pitch.
Any run works here: the calculator converts it to a rise per 12.
Common roof pitches and multipliers
Scroll sideways to see every column.
| Pitch | Angle | Multiplier |
|---|---|---|
| 3/12 | 14.0° | 1.031 |
| 4/12 | 18.4° | 1.054 |
| 6/12 | 26.6° | 1.118 |
| 8/12 | 33.7° | 1.202 |
| 10/12 | 39.8° | 1.302 |
| 12/12 | 45.0° | 1.414 |
Multiply the building footprint by the multiplier to get roof area, then use the roofing square calculator for squares and bundles.
Why pitch changes the price
Steeper roofs have more surface, need more safety setup and go slower. Many price sheets add a steep charge above a set pitch and another for a second story. The slope labels above are a rough guide; each crew and each manufacturer's instructions set the real limits. When Alvin builds a proposal from a measurement report and your price sheet, the pitch and story lines come from the report, and you review the numbers before anything is sent.
Frequently asked questions
What is a 6/12 roof pitch in degrees?
About 26.6 degrees. The roof rises 6 inches for every 12 inches of horizontal run, and the pitch multiplier is 1.118.
What is the pitch multiplier?
It is the number that converts flat area to sloped roof area: the square root of 1 plus the pitch fraction squared. For 8/12 it is 1.202, so a 1,000 square foot footprint has about 1,202 square feet of roof.
What pitch is too low for shingles?
Shingle manufacturers publish a minimum slope and special underlayment rules for low slopes. The limit depends on the product, so check the installation instructions for the shingle you are using and your local code.
The math is the easy part. Alvin does the office work after it.
Alvin is the personal assistant for home services businesses. Your team asks in the app or forwards an email, and Alvin does the work across QuickBooks, your CRM and your suppliers. Anything that spends money or goes to a customer waits for your approval.