Rafter Calculator » Length Calculator

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Our premium pole barn kits come standard with pre-engineered trusses but building rafters is another viable DIY option for smaller span structures.

Roof Calculator & Charts
Pole Barns Design Options
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Roof Pitch Calculator
Truss Calculator
Rafter Calculator
Soil Rating for Pole Embedment
Insulation R Value
Squaring Building Lines Example

Our roof rafter calculator tools are handy for calculating the number of rafters needed, rafter length calculator, lineal feet of rafter, board feed in ridge and sub-facia,and the total board feet in the roof.

Rise and Run means that a 6/12 pitch roof has 6" of rise (vertical) for each foot of run (horizontal).

Pitch Rise / Run (in)	Approx Slope (degrees)
1/12	5°
2/12	10°
3/12	14°
4/12	18°
5/12	23°
6/12	27°
7/12	30°
8/12	34°
9/12	37°
10/12	40°
11/12	42°
12/12	45°

Get exact slope using our Roof Pitch Calculator.

Rafter Length Calculator
Building Width (FT)	Beam Width (In)	Overhang (In)	Pitch (0-12)
ft	in	in	/12

Trying to find what size lumber to use?
This is based upon the span of the rafter (horizontal span, not total rafter length), live and dead loads. To size joists and rafters use the Maximum Span Tables for southern yellow pine. This Rafter Span Calculator is species specific for Douglas Fir, hemlock, etc.

More Roof Calculators
Roof Truss Calculator
How To Cut Rafters

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Roof Rafter Calculator

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