Quantity · Roof pitch
Roof Pitch Calculator
Convert rise/run or a measured angle into pitch (X/12), degrees, and the area multiplier that turns footprint into roof square footage — plus a practical walkability note.
How you measured
Roof pitch
6/12
26.57° · area ×1.118
- Angle
- 26.57°
- Area multiplier
- ×1.118
Walkability
Walkable
How to use the multiplier
Roof surface ≈ building footprint × 1.118. Example: 1,000 sq ft footprint → 1,118 sq ft of roof.
Price data updated . National US ranges from published supplier and contractor averages. Not a bid. Local quotes vary.
How roof pitch is calculated
US residential pitch is stated as rise over a 12-inch run. Angle and area factor follow from that ratio.
pitch ratio = rise_in ÷ 12 angle_deg = atan(rise_in ÷ 12) × 180 ÷ π multiplier = √(1 + (rise_in ÷ 12)²) from angle: rise_in = 12 × tan(angle_deg × π ÷ 180) from feet: rise_in = (rise_ft ÷ run_ft) × 12
Worked example. A 6/12 pitch: angle = atan(0.5) ≈ 26.57°, multiplier = √(1 + 0.25) = 1.118. A 1,800 sq ft footprint becomes about 2,012 sq ft of roof before waste — roughly 20.1 squares.
Roof pitch chart (angle & area multiplier)
The reference people screenshot and link. Walkability notes are field guidance, not OSHA labels — always follow your crew's safety rules.
| Pitch | Angle | Area × | Walkability |
|---|---|---|---|
| 1/12 | 4.76° | 1.003 | Low slope — check membrane requirements |
| 2/12 | 9.46° | 1.014 | Low slope |
| 3/12 | 14.04° | 1.031 | Low slope / walkable with care |
| 4/12 | 18.43° | 1.054 | Walkable |
| 5/12 | 22.62° | 1.083 | Walkable |
| 6/12 | 26.57° | 1.118 | Walkable |
| 7/12 | 30.26° | 1.158 | Steeper — experienced crews |
| 8/12 | 33.69° | 1.202 | Steep — staging often required |
| 9/12 | 36.87° | 1.250 | Steep — staging required |
| 10/12 | 39.81° | 1.302 | Very steep — staging required |
| 12/12 | 45.00° | 1.414 | Very steep — staging required |
Roof pitch calculator FAQ
- What does a 6/12 roof pitch mean?
- The roof rises 6 inches for every 12 inches of horizontal run. That is a 26.57° angle and an area multiplier of about 1.118 — so roof surface is roughly 11.8% larger than the building footprint.
- How do I measure roof pitch?
- On a rafter or a level 12-inch run, measure the vertical rise in inches — that number is the X in X/12. From the ground you can also measure rise and run in feet over a section of the slope and convert. A pitch app or angle finder gives degrees; this calculator converts either way.
- What is a roof pitch area multiplier?
- It converts flat footprint area into actual roof surface area. Multiply footprint square feet by the multiplier for your pitch. Steeper roofs have larger multipliers because the surface stretches.
- What pitch is walkable?
- Many crews treat about 4/12 to 7/12 as walkable with normal caution. Below 4/12 is low slope (often a membrane conversation). Above 8/12 usually needs staging or roof jacks — production slows and cost goes up.
- Does pitch change how many shingles I need?
- Yes. Material quantity follows roof surface area, not footprint. Convert with the multiplier, divide by 100 for squares, then add waste. The roofing square calculator does that end-to-end; use the cost calculator next to price the job.
Next: squares, then cost
Convert footprint → squares & bundles → · Now estimate what this will cost → · All roofing calculators