Shed Roof Slope Calculator

Professional Roofing Tool for Contractors - Calculate Slope, Angle, Pitch & Rafter Length

Professional Use Disclaimer: This tool provides calculations based on standard mathematical formulas. Results are estimates for planning purposes. Always verify measurements on-site and consult local building codes before construction. The developer assumes no liability for construction decisions based on these calculations.

Units:

Enter Rise and Run

Rise (Height)

Run (Horizontal Distance)

Rise is the vertical height, Run is the horizontal distance.

Limitations & Important Notes

Calculations assume simple right triangle geometry for standard shed roofs
Does not account for roof overhangs, eaves, or material thickness
Rafter length is theoretical centerline - actual cutting dimensions may differ
Local building codes may have specific requirements not addressed here
For complex roofs, irregular shapes, or non-standard constructions, consult a structural engineer
Always perform on-site verification before cutting materials or beginning construction
Weather conditions, material variations, and site specifics can affect actual requirements

Professional Recommendation: Use this tool for planning and estimation. Verify all critical measurements with physical tools on-site before proceeding with construction.

Sample Calculations for Reference

Method 1: Rise & Run

Input: Rise = 4 ft, Run = 12 ft

Output: 33.33% slope, 18.43°, 4:12 pitch, 12.65 ft rafter

Method 2: Angle & Run

Input: Angle = 30°, Run = 10 ft

Output: 57.74% slope, 30.00°, 6.93:12 pitch, 11.55 ft rafter

Method 3: Slope % & Run

Input: 25% slope, Run = 8 m

Output: 25.00% slope, 14.04°, 3:12 pitch, 8.25 m rafter

Method 4: Pitch & Run

Input: 4:12 pitch, Run = 24 ft

Output: 33.33% slope, 18.43°, 4:12 pitch, 25.30 ft rafter

Method 5: Trigonometry

Input: Adjacent = 12 ft, Opposite = 3 ft

Output: 25.00% slope, 14.04°, 3:12 pitch, 12.37 ft rafter

Metric Example

Input: 40% slope, Run = 3.5 m

Output: 40.00% slope, 21.80°, 4.8:12 pitch, 3.77 m rafter

Sample values shown are calculated using standard trigonometric formulas for reference purposes.

How to Use This Roof Slope Calculator

Step 1: Choose Your Input Method

There are 5 different ways to calculate your shed roof slope. Pick the one you have measurements for:

Rise & Run - You know vertical rise and horizontal run
Angle & Run - You know the roof angle in degrees and run
Slope % & Run - You know slope percentage and run
Pitch & Run - You know roof pitch (like 4:12) and run
Trigonometry - You know adjacent (run) and opposite (rise) sides

Step 2: Choose Your Units

Select Imperial or Metric units based on your measurement system. Imperial uses feet and inches. Metric uses meters and centimeters.

Step 3: Enter Your Measurements

Enter your numbers in the appropriate fields. Ensure you're using consistent units throughout your measurements.

Step 4: Calculate Results

Click the Calculate button to process your measurements using standard geometric formulas.

Step 5: Review Your Results

You will see multiple results presented:

Slope Percentage - Useful for drainage and material specifications
Roof Angle - In degrees, helpful for cutting and framing
Roof Pitch - Traditional X:12 format used in construction
Rafter Length - Theoretical centerline length for material estimation
Total Rise & Run - Overall dimensions for planning

Practical Application Examples

Example 1: Planning a shed with 4 foot rise over 12 foot run. Enter Rise=4, Run=12 (feet). Results show 33.33% slope, 18.43° angle, 4:12 pitch, rafter length 12.65 ft.

Example 2: Designing a roof with 30° angle and 10 foot run. Enter Angle=30, Run=10 (feet). Results show 57.74% slope, 30° angle, 6.93:12 pitch, rafter length 11.55 ft.

Example 3: Meeting code requirement of 25% minimum slope with 8 meter run. Enter Percentage=25, Run=8 (meters). Results show 25% slope, 14.04° angle, 3:12 pitch, rise=2 meters.

Best Practices for Contractors

Double-check field measurements before relying on calculations
Add appropriate margins for cutting and fitting
Consider local building codes and material requirements
Use results as planning estimates, not final construction dimensions
For critical projects, consult with structural professionals
Document calculations alongside on-site verifications