Roof Pitch Calculator
Roof angle, pitch percentage, rafter length and roof area per metre of length.
Results
Angle
26.57
°
Slope
50.00
%
Length
4.472
m
Area
8.944
m²/m
What this tool does
Give the full span and the ridge height above the wall plate and the calculator returns the pitch and the rafter length. The last figure is the roof surface per metre of building length, which is what sizes the covering.
Formula
angle = atan(height ÷ half-span) ; length = √(height² + half-span²)
Variables
| Symbol | Meaning | Unit |
|---|---|---|
s | Width | m |
h | Height | m |
A | Angle | ° |
P | Slope | % |
R | Length | m |
AR | Area | m²/m |
Worked example
- Width8 m
- Height2 m
- Angle26.57 °
- Slope50.00 %
- Length4.472 m
- Area8.944 m²/m
Limitations
- For work that must comply with a standard or be signed off, check the result against the applicable code and have it reviewed by a qualified engineer.
- The result is an estimate based only on the values you type. Real situations often include factors this calculator does not know about.