Roof Pitch Calculator
Fast, accurate and free online inheritance tax dachu calculator tool running directly in your browser.
-
1Enter data
Enter content, paste text or load a file from disk. -
2Click the button
The tool will immediately process your data in the browser. -
3Get the result
Copy the finished text or save the file to your device.
return "Result ready in 0.1s";
}
Roof pitch calculator
Provide the height (elevation of the slope) and the horizontal section from the eaves to the ridge. For a symmetrical gable roof, the horizontal section = half the width of the building.
Rate this tool:
Related tools
Other tools you may find usefulRoof slope - why the angle of inclination is crucial in construction
The angle of the roof slope is one of the most important design parameters of every building. It determines not only the aesthetics and architecture of the house, but above all its functionality and structural durability. An appropriate roof slope ensures efficient drainage of rainwater and prevents heavy snow from accumulating during winter, which could overload the roof truss. Moreover, each covering material - whether ceramic roof tiles, metal roofing tiles, bituminous shingles or roofing felt - has a minimum angle of inclination specified by the manufacturer, at which it guarantees full tightness. Errors in calculations may lead to roof leaks, attic moisture and loss of warranty on building materials.
Our advanced online roof slope calculator allows you to easily calculate the roof slope in degrees, percentages and in the form of height to span ratio (vertical/horizontal ratio) based on the basic geometric dimensions of the slope.
How to calculate roof slope? Mathematical formulas of slope
To calculate the slope of the roof slope, you need two dimensions: the height of the roof rise (Rise) and the length of the horizontal projection of the slope (Run):
- Roof slope in percent (%):We calculate by dividing the height of the roof rise by the length of the horizontal projection and multiplying the result by 100. Formula: Slope (%) = (Height / Horizontal length) · 100. For example, if the roof rises 2 meters over a length of 5 meters, the slope is: (2 / 5) · 100 = 40%.
- Roof slope in degrees (degrees):The roof slope is a trigonometric function (tangent arc) of the height to length ratio. Formula: Angle(degree) = arctg(Height / Horizontal length). In our example: arctg(2 / 5) ≈ 21.8 degrees.
Table: Minimum roof slope angles for various roof coverings
The table below shows the recommended and minimum roof slopes in degrees and percentages for the most common roofing materials used in construction:
| Roofing material | Minimum slope angle (degrees) | Minimum slope (percentage) | Technical tips and notes |
|---|---|---|---|
| Ceramic roof tile (overlap) | 22° | approx. 40.4% | Standard for roof tiles. Below this angle, a preliminary covering foil with increased tightness is required. |
| Metal roof tiles | 14° | approx. 24.9% | Popular, light covering. Requires tight installation of battens and counter battens. |
| Trapezoidal sheet | 5° – 8° | approx. 8.7% – 14.0% | Often used on sheds, garages and farm buildings. Requires seals on the overlaps. |
| Bituminous shingle | 11° – 12° | approx. 19.4% – 21.3% | Requires full formwork of the substrate (OSB board or board) and underlay felt. |
| Weldable felt felt (two layers) | 1° – 3° | approx. 1.7% – 5.2% | Perfect solution for flat roofs (terraces, inverted roofs) and garage ceilings. |
Frequently asked questions (FAQ)
What is the conversion factor for roof slope from percentage to degrees?
The conversion is not linear because it is based on trigonometric functions. For example: a 10% slope is 5.7°, a 20% slope is 11.3°, a 30% slope is 16.7°, a 50% slope is 26.6°, and a 100% slope corresponds to an angle of 45 degrees.
What is the optimal roof inclination angle in Poland?
In Polish climatic conditions (moderate rain and snow), steep roofs with an angle of 30 to 45 degrees are most often designed. This slope allows snow to slide by gravity and rainwater to drain freely, and also allows for the development of the attic.
Can a flat roof have a slope of 0 degrees?
No. So-called flat roofs in fact must have a minimum slope (so-called technological slope) ranging from 1% to 3% (approx. 1-2 degrees). The lack of any slope would cause ponding of water, which over time would lead to damage to the waterproofing and leaking of the ceiling.
How to measure the roof slope on a construction site without a computer?
You can use a level that is exactly 1 meter (100 cm) long. Place the level horizontally, resting one end against a rafter or roof batten. Measure the vertical distance (gap) from the other end of the level to the roof surface in centimeters. This distance in cm directly corresponds to the roof slope in percent (e.g. 30 cm difference equals a 30% slope).
Does the angle of the roof affect the cost of construction?
Yes, significantly. The greater the roof inclination angle, the greater the roof surface area with the same building outline. This means using more wood for the truss, foil, membrane and the covering itself (roof tiles, sheet metal), which increases the total investment cost.