How to use the calculator
- Choose single plane for one displacement or rolling for two perpendicular displacements.
- Measure displacement between parallel pipe centerlines, in inches. Rolling values are vertical and sideways magnitudes perpendicular to the original pipe direction.
- Enter the common fitting angle, 0.1°–89.9° in 0.1° increments. Offsets accept 0–100,000 in in 0.01 in increments.
- Calculate centerline travel and run, then compare common angles for the same true offset. Each table row changes only the angle.
- Obtain matching fitting takeoffs and installation dimensions before calculating a cut length. Copy, share or print the geometry with its method and assumptions.
What the results mean
True offset is displacement perpendicular to the original pipe direction. In a rolling offset it combines the vertical and sideways components using the Pythagorean theorem. Travel is the diagonal between fitting centers. Run is its projection along the original direction, also called setback or advance in this worksheet.
The angle table holds the true offset constant and shows how another fitting angle changes travel and run. “More” or “less” is the run difference from your entered angle. A shorter run is a geometric result, not a statement that a fitting or installation is suitable.
Decision notes for the Pipe Offset Calculator
Decision supported: Compare single-plane and rolling-offset centerline geometry and the run needed at different fitting angles.
Sensitivity hint
Small fitting angles increase both travel and run. Increasing either rolling component increases true offset; swapping the two components leaves the centerline lengths unchanged.
What to do next
Compare the computed run with the space in your layout. Use the actual fitting geometry, center-to-end dimensions, sockets or threads, and fit-up requirements to establish a cut length. The calculator deliberately withholds that length.
Save this scenario
Copy retains active measurements, angles, the comparison table and method version. Share restores the selected layout; Print / Save as PDF retains the current geometry. Report an issue with the Pipe Offset Calculator.
Formula / methodology
Single plane: true offset O = entered offset. Rolling: O = √(vertical² + sideways²). For fitting angle θ, travel T = O ÷ sin(θ) and run R = O ÷ tan(θ). The model uses two equal opposite bends connecting parallel directions.
Angles are degrees. Travel and run display to 0.01 in, true offset to 0.001 in, and the entered fitting angle to 0.1°. Intermediate true offset is not rounded before solving the triangle. Tiny positive lengths use a less-than threshold. Table run changes are relative to the unrounded run at the entered angle.
Assumptions and limitations
- Rolling components must be perpendicular to one another and to the original direction. They are magnitudes; left/right and up/down placement are outside this scalar calculation.
- Diameter was removed because it does not change the triangle. It can affect real fitting dimensions, which require separate product data.
- Travel is not a pipe cut length. Finite bend geometry, fitting takeoffs, socket depth, thread engagement and fit-up allowances are outside the model.
- Zero true offset gives zero travel and run without selecting any fitting arrangement. Angles of 0° and 90° are excluded from the supported offset model.
- No pressure, flow, code, support or installation approval is inferred from these dimensions.
Example calculation
Single plane: 12 ÷ sin(45°) gives 16.97 in travel; 12 ÷ tan(45°) gives 12 in run. With the same 12 in offset at 22.5°, travel is 31.36 in and run is 28.97 in.
Rolling: √(12² + 5²) = 13 in true offset. At 45°, the centerline travel is 18.38 in and run is 13 in. A 30° fitting gives 26 in travel and 22.52 in run: 9.52 in more run than 45° for that same true offset.
Entering 18 in and 67.5° gives 19.48 in travel and 7.46 in run; the result retains the entered 67.5° angle.
Common mistakes
- Entering pipe outside diameter as the centerline offset.
- Adding perpendicular rolling components instead of taking their hypotenuse.
- Using radians where the fitting angle is specified in degrees.
- Cutting to centerline travel without applying actual fitting takeoffs.
- Comparing angles after changing offset measurements at the same time.
FAQ
What is a rolling offset?
It combines perpendicular vertical and sideways displacement. The calculator uses their hypotenuse as the true offset, then solves travel and run at the entered fitting angle.
Why is no pipe diameter requested?
Diameter does not enter the centerline triangle. Actual fitting sizes and takeoffs depend on product data and are separate from this geometric result.
Is travel the pipe cut length?
No. Travel is a center-to-center dimension. Actual cut length needs matching fitting takeoffs and connection allowances.
What does the angle table compare?
Every row uses the same true offset and changes only the fitting angle. Its final column shows how much more or less run it needs than the entered angle.
Can I retain a rolling-offset scenario?
Yes. Copy includes active components and the comparison table. Share restores the layout and values; Print / Save as PDF retains the current result and method.
Sources and assumptions
The true-offset and triangle equations are Pythagorean, sine and tangent identities. TNB Positioners: rolling offsets and fitting takeoffs describes the same field terminology and distinguishes center-to-center travel from cut length requiring fitting takeoffs.
Use the equations to inspect the centerline dimensions. Fitting compatibility, connection allowances and installation design remain separate.
Method details
Updated: November 3, 2026. Calculation method: PIPE_OFFSET-1.1. Centerline geometry with single-plane and rolling modes; cut length is outside the model.