Roof Rafter Calculator

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

Roof Calculator & Charts

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).

Rise / Run (in)
Approx Slope (degrees)
Get exact slope using our Roof Pitch Calculator.

Rafter Length Calculator
Roof Width (FT)Ridge Width (In)Overhang (In)Pitch (0-12)
ft in in /12
How to Enter Sizes
24 Feet24
24 Feet 6 inches24 6
24 Feet 6 & 1/2 inches24 6 1/2


roof truss calculation points
A) Roof Length In Feet B) Rafter Length In Feet C) On Center (inches between rafters) D) Rafter Thickness In Inches E) Rafter Width In Inches
ft ft in in in
Ridge Height Calculator
Building Profile Generator

How to Enter Sizes

24 Feet24
24 Feet 6 inches24 6
24 Feet 6 & 1/2 inches24 6 1/2

How To Cut Rafters

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

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