Rolling Offset Calculator
A rolling offset changes both the vertical and horizontal position of a pipe run at the same time. Instead of making two separate offsets, you connect the pipes with a single diagonal piece. Enter your rise and offset distances to calculate the travel length and true offset.
Rolling Offset Formula
A rolling offset combines a vertical rise and a horizontal offset into one diagonal connection. The math involves two steps:
- True offset = square root of (rise² + offset²)
- Travel = true offset / sin(fitting angle)
- Run = true offset / tan(fitting angle)
Example: 12" Rise, 18" Offset with 45-degree Fittings
- True offset = sqrt(12² + 18²) = sqrt(144 + 324) = sqrt(468) = 21.633 inches
- Travel = 21.633 / sin(45) = 21.633 / 0.7071 = 30.594 inches
- Run = 21.633 / tan(45) = 21.633 / 1.0 = 21.633 inches
Choosing Fitting Angles
- 45-degree fittings are the most common for rolling offsets. The travel calculation is the simplest of the three.
- 22.5-degree fittings produce a longer, more gradual offset. Good for drainage where you want to maintain flow.
- 60-degree fittings create a steeper, shorter connection but are less commonly used.
Tips for Accurate Measurements
Measure rise and offset between the centerlines of the two pipes, not the outside edges. Account for fitting takeout (the distance the fitting itself adds) when cutting your pipe.