About Roof Pitch Calculator
Translate roof rise and horizontal run into several common slope formats.
Inputs and calculations stay in your browser and require no signup.
How the calculation works
Planning calculation
Slope = rise ÷ run; angle = arctangent of slope; multiplier = √(1 + slope²).
How to use this calculator
- 1Enter measured project dimensions and quantities.
- 2Adjust material, spacing, waste or density assumptions to match the project.
- 3Review the live planning quantities.
- 4Round purchasing quantities appropriately and confirm field conditions.
Understanding the result
A 6:12 roof rises 6 units per 12 horizontal units, which is a 50% slope and about 26.565°.
Results use the units shown beside each field and output.
Important limitations
- Geometry does not establish rafter size, load capacity, connections or code compliance.
- Use actual horizontal run for rafter length and separately account for overhangs and cuts.
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Frequently asked questions
What angle is a 6:12 pitch?
Approximately 26.565 degrees.
Is pitch the same as percent slope?
They describe the same slope differently; 6:12 equals 50%.
Does this size rafters?
No. It calculates geometry only.
Use with
These tools support a practical next or previous step in the same workflow.
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