Birdsmouth Cut Calculator
Result
Birdsmouth Cut Calculator Calculate the dimensions of a birdsmouth cut (seat cut and plumb cut) for a roof rafter based on roof pitch. — free online calculator.
Formula
- Birdsmouth Cut Calculator calculates its result from Rise, Run, Rafter Width. It uses the formula Angle = atan(rise/run); Seat = rafter width × cos(angle); Plumb = rafter width × sin(angle). Change any input to recalculate the result instantly.
- The main inputs are Rise, Run, Rafter Width. Enter them in the units and format shown in the calculator.
- Keep measurements and project assumptions consistent before comparing or combining values.
- Changing any input above recalculates the result with the same calculation engine used by this page.
Example: Birdsmouth Cut
- Rise: 2
- Run: 3
- Rafter Width: 4
Using Rise = 2, Run = 3, Rafter Width = 4, the calculated result is 2.2188007849.
Sample result: Calculating…
Frequently asked questions
What does the Birdsmouth Cut calculate?
Birdsmouth Cut Calculator Calculate the dimensions of a birdsmouth cut (seat cut and plumb cut) for a roof rafter based on roof pitch. — free online calculator.
Which values should I enter?
Enter Rise, Run, Rafter Width using the units and format shown beside each field.
What formula does this calculator use?
The calculator uses the following relationship: Angle = atan(rise/run); Seat = rafter width × cos(angle); Plumb = rafter width × sin(angle).
Why might my result differ from another source?
Results can differ when another source uses different units, rounding rules, conventions or assumptions. Compare the inputs and definitions before comparing results.
Does the result update automatically?
Yes. Changing an input updates the result using the same calculation engine shown on this page.