Rolling Offset Calculator
Calculate true offset distance, travel spool length, and roll angle for 3D compound pipe transitions.
True Offset = √(Rise² + Roll²). Travel is calculated by multiplying True Offset by the fitting constant (1.414 for 45°).
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How Rolling Offsets Work in 3D Space
A standard offset changes direction in a single plane (e.g. rising vertically). A rolling offset changes direction in both the vertical and horizontal planes simultaneously.
True Offset = √(Rise² + Roll²)
Center-to-Center Travel = True Offset / sin(Fitting Angle)
Cut Pipe Length = Travel - (2 × Fitting Takeout)
Roll Angle = arctan(Roll / Rise)
Frequently Asked Questions
Why is 1.414 used for 45-degree offsets?
Because 1 / sin(45°) = 1 / 0.7071 = 1.4142. Multiplying the offset by 1.414 gives the hypotenuse (travel length) instantly.
How do you set the roll angle on the job site?
Use a digital magnetic level or framing square. Set the first fitting, rotate it to the calculated roll angle (e.g. 36.9° from vertical), and lock in place before tack welding.
Why must 2x takeout be deducted from travel?
The travel length is measured center-to-center of the two elbows. Both fittings extend toward each other by their center-to-face takeout distance, so you must subtract both takeouts to find the cut pipe spool length.