Pendiente de tejado: ángulo, porcentaje y desnivel

Calcula ángulo, pendiente porcentual y de tejado (x en 12), longitud inclinada y factor de cabio a partir del desnivel y la distancia horizontal.

Actualizado Ejemplos verificados: 8

Negative for a downhill slope
Probar
Ángulo
°
Ángulo: 26.5651 °
Máximo de decimales: 4; Al más cercano; empates alejándose de cero
Calificación
50%
Roof pitch
6in 12
Ratio (rise : run)
1 : 2
Rise per unit of run
0.5
Rafter length factor
1.118034
Slope length
13.4164cm

This slope rises 0.5 for every 1 of run: 26.57° from horizontal, a 50 % grade, or a 6/12 roof pitch. Its sloped length is 13.4164 cm.

Slope profile, to scale

run 12 cmrise 6 cm26.57°6/12 pitch · 50 %
Cómo se calcula S
  1. Slope

    m=riserun=612=0.5m = \frac{\text{rise}}{\text{run}} = \frac{6}{12} = 0.5
  2. Ángulo

    θ=arctan⁡m=arctan⁡0.5=26.565051∘\theta = \arctan m = \arctan 0.5 = 26.565051^\circ
  3. Grade and pitch

    grade=100m=50 %,pitch=12m=6 in 12\text{grade} = 100m = 50\,\%,\qquad \text{pitch} = 12m = 6 \text{ in } 12
  4. Rafter factor

    1+m2=1+0.52=1.118034\sqrt{1 + m^2} = \sqrt{1 + 0.5^2} = 1.118034

    Multiply a horizontal run by this to get the sloped length.

  5. Slope length

    rise2+run2=12×1.118034=13.416408 cm\sqrt{\text{rise}^2 + \text{run}^2} = 12 \times 1.118034 = 13.416408\,\text{cm}

Acerca de Pendiente de tejado: ángulo, porcentaje y desnivel

Every way of stating a slope comes from one ratio, m = rise ÷ run. The angle from horizontal is arctan m, the percent grade is 100m, the roof pitch is 12m (units of rise per 12 of run), and the rafter factor √(1 + m²) turns a horizontal run into the sloped length. Enter a rise and run, or any one of the other forms, and the rest follow.

The default rise of 6 over a run of 12 is a 6/12 roof: 26.57°, a 50% grade and a rafter factor of 1.1180, so 12 cm of run needs 13.4164 cm of rafter. Ramps and roads use the same numbers: the steepest ramp the 2010 ADA Standards allow, 1:12, is an 8.33% grade, or 4.76°.

Percent grade is not an angle: a 100% grade is 45°, and a vertical face has no finite grade or pitch, so angles must lie between −90° and 90°. A negative rise describes a downhill slope.

Ejemplos resueltos

Rise 6, run 12 (a 6/12 roof)

Medida conocida
Rise and run
Rise
6 cm
Run (horizontal distance)
12 cm
Unidad de los resultados
Centímetros (cm)
Ángulo
26.565051 °
Calificación
50%
Roof pitch
6 in 12
Ratio (rise : run)
1 : 2
Rafter length factor
1.118034
Slope length
13.416408 cm

Fuente de comprobación: Python 3.8 math: degrees(atan(0.5)), sqrt(1.25), sqrt(6**2 + 12**2)

45°

Medida conocida
Ángulo
Angle from horizontal
45 °
Calificación
100%
Roof pitch
12 in 12
Ratio (rise : run)
1 : 1
Rafter length factor
1.414214

Fuente de comprobación: tan 45° = 1; Python 3.8 math.sqrt(2)

8 % road grade

Medida conocida
Percent grade
Calificación
8%
Ángulo
4.573921 °
Roof pitch
0.96 in 12
Ratio (rise : run)
1 : 12.5

Fuente de comprobación: Python 3.8 math: degrees(atan(0.08)); 12 × 0.08; 1/0.08

4/12 roof pitch

Medida conocida
Roof pitch
Pitch
4 in 12
Ángulo
18.434949 °
Calificación
33.333333%
Rafter length factor
1.054093

Fuente de comprobación: Python 3.8 math: degrees(atan(4/12)), sqrt(1 + 1/9)

Preguntas

How do you convert percent grade to degrees?

Take the arctangent of the grade divided by 100: θ = arctan(grade/100). An 8% road grade is arctan 0.08 = 4.57°, and a 100% grade is 45°, not 90°. The reverse is grade = 100 × tan θ, so a 30° slope is a 57.7% grade.

What angle is a 6/12 roof pitch?

26.57°. A pitch of x/12 means x units of rise for every 12 of run, so the angle is arctan(x/12): 4/12 is 18.43°, 6/12 is 26.57°, 8/12 is 33.69° and 12/12 is 45°. The rafter factor for 6/12 is √1.25 = 1.118, so 12 ft of horizontal run needs 13.42 ft of rafter before any overhang.

What is the maximum slope for a wheelchair ramp?

1:12 under the 2010 ADA Standards for Accessible Design (§405.2): one unit of rise for every 12 of run, an 8.33% grade or 4.76°. Each ramp run may rise at most 30 in (§405.6), so a 30 in rise needs a run of at least 30 ft. Other countries set their own limits in their building codes.

How do you calculate rise over run?

Divide the vertical rise by the horizontal run, both in the same unit: m = rise/run. A roof that rises 6 in over 12 in of run has m = 0.5. Measure the run horizontally, not along the surface: the sloped length here is 13.42 in, and dividing by it gives 0.447, the sine of the angle rather than the slope.

¿Qué precisión tiene «Pendiente de tejado: ángulo, porcentaje y desnivel»?

La precisión depende de tus datos y de los supuestos del método. El cálculo decimal usa 50 cifras significativas, pero las estimaciones, los métodos numéricos y los datos de origen pueden ser menos precisos; el redondeo mostrado no elimina esos límites. Ejemplos resueltos comprobados con fuentes independientes: 8. Por ejemplo, «Rise 6, run 12 (a 6/12 roof)» se comprueba con Python 3.8 math: degrees(atan(0.5)), sqrt(1.25), sqrt(6**2 + 12**2).

¿De dónde procede el método?

OpenStax College Algebra 2e, §4.1 — slope as rise over run; US Access Board, ADA Standards §405.2 — ramp slope 1:12 (8.33 %).

Acerca de esta calculadora

m=riserun,θ=arctan⁡m,grade=100m %pitch=12m in 12,factor=1+m2\begin{gathered} m = \frac{\text{rise}}{\text{run}},\quad \theta = \arctan m,\quad \text{grade} = 100m\,\% \\[6pt] \text{pitch} = 12m \text{ in } 12,\quad \text{factor} = \sqrt{1 + m^2} \end{gathered}

Fuentes

  1. OpenStax College Algebra 2e, §4.1 — slope as rise over run
  2. US Access Board, ADA Standards §405.2 — ramp slope 1:12 (8.33 %)

Verificado con las referencias

Esta calculadora incluye 8 ejemplos resueltos con respuestas de fuentes independientes. Forman parte del conjunto de pruebas y también puedes ejecutarlos aquí.

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