Roof Pitch Calculator
Roof pitch is expressed as rise-over-run — how many inches the roof rises for every 12 horizontal inches. A 6/12 pitch rises 6 inches per foot. This calculator converts pitch to degree angle, slope percentage, rafter length multiplier, and ridge board height — everything you need to plan rafters and order materials.
Buy MaterialsAD
Top PickSpeed Square (Swanson) — Amazon~$13.99* Affiliate links — we may earn a commission at no cost to you.
Related Calculators
How to Use This Calculator
- 1Enter your measurements in the fields above. Use the units shown next to each field (ft, in, etc.).
- 2Click Calculate to get your material estimate instantly.
- 3Review the highlighted result — it shows the key quantity you need to order.
- 4Use Copy Results to save your estimate, or bookmark the URL — your inputs are encoded in the link.
Pro tip: Always add 10% to your material order to account for waste, cuts, and defects.
Frequently Asked Questions
What is a good roof pitch?
A 4/12 to 6/12 pitch is considered standard for most residential roofs — gentle enough for safe walking but steep enough for proper water drainage. Asphalt shingles require at least a 2/12 pitch; metal roofing can go as low as 1/12 with standing seam panels.
How do I measure roof pitch without getting on the roof?
Place a level against the roof from the attic, making it horizontal (check the bubble). Measure up 12 inches from one end, then measure from that point straight up to the underside of the roof sheathing. That measurement in inches is your pitch. Example: 6 inches up = 6/12 pitch.