Roof Calculator | Roof Interior Space | Roof Pitch

Roof Calculator

Calculates height, length and width of a gable roof from the angle of slope and the thickness of the roof. 45° is a standard value for the slope α, for the thickness of the roof r, 30 cm are assumed. The height h means height above base, not height above ground. Example: at a base width b of 500 cm, the height is 292.43 cm.

Please enter angle of slope, thickness of the roof and length, width or height. The other two values and the thickness of the ridge will be calculated. All length units are the same (e.g. cm or feet), the angle is in degrees. The dimensions are rounded to two decimal places. Length of one roof side is without eaves.

* Angle of slope (α):		°
* Roof thickness (r):
Length of one roof side (a):
Base width (b):
Roof height (h):
Ridge thickness (s):

This calculator is used to determine and illustrate a few important dimensions of a roof. It is not an independent planning tool for building a house and neglects other aspects such as material, appearance and statics. The calculation is carried out using trigonometric functions. An example of one of these is the height of the roof, which is calculated from the angle of slope, the length of one side of the roof and the thickness of the ridge of the roof with h=a*sin(α)+s.

An example with the roof under which this calculator was developed: The angle of slope is around 30 degrees. The thickness of the roof is not known exactly, but is assumed to be the specified 30 centimeters. The base width measured with Google Earth is 11.20 meters, i.e. 1120 centimeters. This means that one side of the roof is about 6.7 meters long and the roof is 3.58 meters high at the ridge. If you want to measure this height, you have to remember that the floor rests on the base and also has a significant height and that the thickness of the roof ridge must be added to this when measuring inside. The internal height measured in the example from the floor to the roof ridge is about three meters, which results in a floor thickness of 23 centimeters, but the measurement of the angle of inclination was not done to the exact degree, so the values ​​are only approximate.

Last updated on 06/25/2025. Author: Jürgen Kummer

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