Roof Rise Calculator
Calculate roof rise from roof pitch and either full building span or horizontal run. Add wall or eave height to estimate total ridge height above the same reference level.
Example: a 24 ft wide symmetrical gable roof with a 6/12 pitch has a 12 ft horizontal run. The roof rises 6 ft from the wall line to the ridge. If the wall/eave reference height is 9 ft, the estimated total ridge height is 15 ft.
What Is Roof Rise?
Roof rise is the vertical distance from the roof's wall or eave reference line to the ridge. It is not the same as rafter length, roof area or the total height of the building.
Roof pitch tells you how much vertical rise occurs for a given horizontal run. A 6/12 roof rises 6 units for every 12 units of horizontal travel.
For a simple symmetrical gable roof, the horizontal run is normally half of the full building span. A 24 ft span therefore gives a 12 ft run.
Calculate Roof Rise & Ridge Height
Enter roof pitch and either building span or horizontal run. Wall/eave height is optional and is only needed when you want an estimated total ridge height.
Enter roof pitch and building span or horizontal run to calculate roof rise.
How to Use the Roof Rise Calculator
Use pitch with either full building span or horizontal run. Wall height is optional.
Enter Roof Pitch
Enter the rise for a standard 12-unit run, such as 4/12, 6/12 or 8/12.
Choose Span or Run
Enter full building span for a simple symmetrical gable roof, or use horizontal run if you already know it.
Add Wall Height if Needed
Wall/eave height is optional. Add it when you want an estimated total ridge height above the same reference level.
Roof Rise Formula
Roof rise comes directly from horizontal run and roof pitch.
From Horizontal Run
Convert the X/12 pitch into a rise-to-run ratio.
For a 12 ft run at 6/12:
From Building Span
On a simple symmetrical gable roof, calculate run first.
For a 24 ft span:
Roof Rise vs. Total Ridge Height
These measurements describe two different vertical distances.
Roof Rise
6 ftThe vertical increase from the wall/eave roof reference line to the ridge for the 24 ft, 6/12 example.
Total Ridge Height
15 ftIf the compatible wall/eave reference is 9 ft high, then 9 ft + 6 ft roof rise = approximately 15 ft.
Roof Rise for a 24 ft Building Span
With a symmetrical gable roof, a 24 ft full span produces a 12 ft horizontal run.
| Roof Pitch | Angle | Horizontal Run | Rise to Ridge |
|---|---|---|---|
| 2/12 | 9.46° | 12 ft | 2 ft |
| 4/12 | 18.43° | 12 ft | 4 ft |
| 6/12 | 26.57° | 12 ft | 6 ft |
| 8/12 | 33.69° | 12 ft | 8 ft |
| 10/12 | 39.81° | 12 ft | 10 ft |
| 12/12 | 45° | 12 ft | 12 ft |
Common Ridge Height Calculation Mistakes
The math can be simple while the underlying measurement assumptions are wrong.
For a symmetrical gable roof, run is normally half of the full span.
Roof rise only describes the vertical roof geometry above the wall/eave reference.
Wall height and roof rise must be measured from compatible levels before adding them.
An off-center ridge or unequal roof planes cannot be modeled by simply dividing span by two.
Ridge boards, trusses, structural depths and other details can affect actual field dimensions.
Verify the actual structural or wall-to-wall span relevant to the roof geometry.
How We Calculate Roof Rise
The calculator uses the roof pitch ratio to determine how much vertical rise occurs over the horizontal run.
For X/12 pitch, the ratio is X divided by 12. Multiplying that ratio by horizontal run gives the geometric roof rise.
When full building span is entered, the calculator divides the span by two before calculating rise. This assumes a simple symmetrical gable roof with the ridge centered over the span.
Wall/eave height is not required to calculate roof rise. It is only added when estimating total ridge height.
Results should be treated as geometric measurement references, not structural design dimensions.
Before Using the Result
- Confirm the roof is actually symmetrical if using full span.
- Verify the roof pitch.
- Confirm span or run from reliable measurements.
- Use compatible reference elevations for wall and ridge height.
- Check framing or structural drawings for construction dimensions.
Related Roofing Calculators & Guides
Continue from vertical roof rise into rafter length, roof area and material estimating.
Roof Rise Calculator FAQs
How do I calculate roof rise?
Multiply horizontal run by the pitch rise divided by 12. For example, a 12 ft run at 6/12 pitch rises 6 ft.
What is the roof rise for a 24 ft wide building at 6/12 pitch?
For a simple symmetrical gable roof, the run is 12 ft. A 6/12 pitch therefore produces 6 ft of vertical roof rise.
Is roof rise the same as ridge height?
No. Roof rise is the vertical roof dimension above the wall/eave reference. Total ridge height also includes the compatible wall or reference height below it.
What is the difference between span and run?
Span is the full horizontal width used by the roof. On a symmetrical gable roof, horizontal run is normally half the span.
Can I calculate ridge height without wall height?
You can calculate roof rise without wall height, but you need a compatible wall/eave reference height if you want total ridge height above that reference level.
Does this work for hip roofs or asymmetric roofs?
The full-span mode assumes a simple symmetrical gable roof. Other geometries may require separate runs, roof planes or construction-specific calculations.
Can I use feet or meters?
Yes. The calculator supports both feet and meters. Keep all related measurements in the selected unit.
Calculate Your Roof Rise
Enter roof pitch and span or run to calculate vertical rise, roof angle and estimated ridge height.
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