Rolling Offset Calculator
Calculate the exact travel length and run for pipe rolling offsets in plumbing, conduit, and HVAC installations. Enter the vertical and horizontal offset distances and select your fitting angle.
Vertical distance between the two pipe centerlines
Horizontal distance between the two pipe centerlines
Used for center-to-center measurements
What is a rolling offset in plumbing?
A rolling offset is a pipe fitting technique used when two pipes need to be connected but are not aligned both vertically and horizontally. It combines a vertical offset (rise) with a horizontal offset (roll) using angled fittings. The rolling offset is common in plumbing, HVAC, and conduit installations where pipes must navigate around obstacles while changing elevation and lateral position simultaneously.
How do you calculate the travel length for a rolling offset?
First calculate the true offset: √(vertical² + horizontal²). Then divide by the sine of the fitting angle. For a 45-degree fitting: Travel = √(offset² + roll²) ÷ sin(45°). For 12in vertical and 8in horizontal: √(12² + 8²) = 14.42in true offset, then 14.42 ÷ 0.7071 = 20.4in travel length. The run (horizontal advancement) = Travel × cos(fitting angle).
What is the most common fitting angle for rolling offsets?
45-degree fittings are the most commonly used for rolling offsets because they offer the best balance of offset distance and travel length. They provide enough directional change without excessive flow restriction. 30-degree fittings create a gentler bend with longer travel, while 60-degree fittings make tighter turns suitable for constrained spaces. 22.5-degree fittings are used when space allows for gradual transitions.
How does pipe diameter affect rolling offset calculations?
Pipe diameter affects center-to-center measurements. The calculator provides the centerline travel length, but for cut length you must subtract the fitting make-up (the distance the pipe inserts into each fitting). Each fitting manufacturer provides make-up values for their products. For threaded fittings, measure from the face of the fitting to the shoulder inside. For welded fittings, subtract the fitting radius.