Roof Pitch Calculator
Use this roof pitch calculator to convert between rise, run, pitch percentage, roof angle, and rafter length. It is a quick planning tool for gable, shed, and other sloped roofs.
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Quick Answer:
Roof pitch is rise ÷ run. Multiply that ratio by 100 for pitch percent, or use arctan to convert it to degrees.
What This Roof Pitch Calculator Helps You Do
Use this roof pitch calculator to convert between rise, run, pitch percentage, roof angle, and rafter length. It is a quick planning tool for gable, shed, and other sloped roofs.
How to Calculate Roof Pitch Calculator
- Measure the roof pitch inputs - Enter the dimensions, density, spacing, or thickness values shown on the page.
- Check the units - Keep every input in the same unit system so the result stays consistent and easy to compare.
- Choose the solve mode - Select the calculation you want to run, such as weight, volume, cost, count, or angle.
- Read the output - Use the main result and the extra detail rows to verify the estimate before you order materials or build.
Roof Pitch Calculator Formula
pitch = rise / run
| Symbol | Definition | Unit |
|---|---|---|
| rise | Vertical rise | ft |
| run | Horizontal run | ft |
| p | Pitch percent | % |
| L | Rafter length | ft |
Worked Examples
USA - Standard gable roof
- rise: 1.5
- run: 6
- pitchPercent: 0
- pitchAngle: 0
- pitchRatio: 0
- rafterLength: 0
Result: Roof pitch = 25.00 %
A 1.5 ft rise over a 6 ft run is a common pitch check. The estimate is 25.00 %.
UK - Shed roof angle
- rise: 2
- run: 8
- pitchPercent: 0
- pitchAngle: 0
- pitchRatio: 0
- rafterLength: 0
Result: Roof angle = 14.04 deg
Angle is the easiest way to compare roof slope with code guidance. The estimate is 14.04 deg.
EU - Rafter length check
- rise: 3
- run: 9
- pitchPercent: 0
- pitchAngle: 0
- pitchRatio: 0
- rafterLength: 0
Result: Rafter length = 9.49 ft
Rafter length helps when you are ordering framing lumber. The estimate is 9.49 ft.
GCC - Roof ratio quick check
- rise: 2.5
- run: 10
- pitchPercent: 0
- pitchAngle: 0
- pitchRatio: 0
- rafterLength: 0
Result: Roof pitch ratio = 3.00 :12
The 12-based ratio is a fast way to talk about pitch on site. The estimate is 3.00 :12.
How to Interpret Your Results
| Range | Meaning | Action |
|---|---|---|
| < 4:12 | Low pitch | Usually needs careful material selection and drainage planning. |
| 4:12–9:12 | Conventional pitch | Common for most houses and sheds. |
| > 9:12 | Steep pitch | Check access, safety, and extra roofing fasteners. |
Frequently Asked Questions
It estimates the main planning quantity for roof pitch work using the formula shown on the page. That gives you a practical number before you order materials, compare suppliers, or talk to a contractor. Roof pitch affects rafter length, roof area, and shingle selection.
Enter the values that match the unit labels beside the fields. If the page expects feet, inches, gallons, pounds, or watts, keep everything in that unit family so the result stays reliable.
The calculator multiplies or divides the main quantity by the values you enter, so every measurement feeds directly into the final answer. A small change in depth, area, density, or factor can make a large difference on a bigger project.
Yes, as long as the units stay consistent within the calculation. If the page expects feet, inches, gallons, or pounds, convert first so the final result is accurate and easy to interpret.
Treat the result as a planning estimate. Use the main output for sizing or ordering, then review the detail rows for waste, weight, cost, or conversion notes before you finalize the purchase.
Yes if the job involves cut losses, uneven ground, spill risk, or irregular shapes. A small allowance is usually safer than ordering exactly to the bare math, especially for roof pitch projects that are hard to top up later.
It is exact for the numbers you enter, but real-world projects can still vary because of compaction, tolerances, site conditions, and product differences. Use the result as a solid working estimate, not a final structural or procurement check.
Yes. That is one of its main uses. The result helps you estimate how much to buy, what it may weigh, and what the budget might look like before you place an order or request a quote.
Disclaimer: This calculator provides planning estimates only. Confirm local roofing codes, snow loads, and framing requirements before building.
Sources
Last reviewed: March 2026