Calculator Inputs
Use one consistent unit for all length inputs. The responsive calculator grid uses three columns on large screens, two on medium screens, and one on mobile screens.
Example Data Table
| Scenario | Span | Method | Input | Wall Height | Rise | Total Ridge Height |
|---|---|---|---|---|---|---|
| Residential Gable | 30 ft | Pitch Ratio | 6 in 12 | 10 ft | 7.5 ft | 17.5 ft |
| Garage Roof | 24 ft | Angle | 22° | 9 ft | 4.85 ft | 13.85 ft |
| Workshop Roof | 36 ft | Slope % | 40% | 12 ft | 7.2 ft | 19.2 ft |
| Storage Shed | 18 ft | Direct Rise | 3.5 ft | 8 ft | 3.5 ft | 11.5 ft |
Formula Used
This calculator assumes a symmetrical gable roof. It first converts the full building span into roof run, then calculates rise and other dimensions from the selected method.
1. Roof Run
Run = Span ÷ 2
2. Rise from Pitch Ratio
Rise = Run × (Pitch Rise ÷ Pitch Run)
3. Rise from Roof Angle
Rise = Run × tan(Angle)
4. Rise from Slope Percentage
Rise = Run × (Slope % ÷ 100)
5. Rise from Rafter Length
Rise = √(Rafter² − Run²)
6. Rafter Length to Ridge
Rafter = √(Run² + Rise²)
7. Total Ridge Height
Total Ridge Height = Wall Height + Rise
8. Roof Angle
Angle = arctan(Rise ÷ Run)
9. Roof Edge Length with Overhang
Roof Edge Length = (Run + Overhang) × Slope Factor
10. Roof Area Estimate
Roof Face Area = Roof Edge Length × Building Length
Total Roof Area = Roof Face Area × 2
How to Use This Calculator
- Select a measurement unit and stay consistent with it.
- Choose the calculation mode that matches your known roof data.
- Enter the building span, wall or eave height, and overhang.
- Fill only the mode-specific values, such as pitch, angle, or rafter length.
- Optionally enter building length to estimate total roof area.
- Choose decimal precision for cleaner output.
- Press Calculate Roof Height to show the result above the form.
- Review the result cards, table, and Plotly chart.
- Download the result as CSV or PDF if needed.
Frequently Asked Questions
1. What does roof height mean in this calculator?
Roof height is the rise from the wall plate to the ridge. The calculator also shows total ridge height after adding the wall or eave height.
2. What is the difference between span and run?
Span is the full building width. Run is half the span for a symmetrical gable roof. Most roof height formulas use run, not the full span.
3. Can I calculate with angle instead of pitch?
Yes. Select the angle mode, enter the roof angle in degrees, and the calculator converts it into rise, slope percentage, pitch equivalent, and ridge height.
4. Does overhang change the ridge height?
No. Overhang extends the roof edge outward, but it does not change ridge height. It only affects the sloped edge length and area estimate.
5. Is this calculator suitable for all roof shapes?
It is best for symmetrical gable roofs. For hips, gambrels, or asymmetrical roofs, calculate each side separately or use a dedicated roof geometry model.
6. Which unit should I use?
You can use feet, meters, inches, or centimeters. The important rule is consistency. Enter every length in the same unit to keep results correct.
7. Why should I enter wall or eave height?
Wall height lets the calculator report total ridge elevation above the base level. That is useful when planning framing, appearance, and clearance.
8. Are the roof area results exact for ordering materials?
No. They are planning estimates. Final material orders should also consider waste, ridge details, dormers, valleys, laps, and manufacturer installation requirements.