Calculate pipe offset travel, run and cut length for 45° or any fitting angle, for a simple offset or a rolling offset with both rise and roll.
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Compound Pipe Angle Formula
The calculator uses two formulas depending on the mode you pick.
Rolling Offset mode finds the pipe length (travel) between two fittings when the offset goes both up and sideways:
- Rise — vertical offset between the two pipe centerlines
- Roll — horizontal offset between the two pipe centerlines
- True Offset — the diagonal offset the pipe actually spans
- Fitting Angle — the angle of the fittings on each end (45°, 22.5°, etc.)
- Travel — the center-to-center distance before subtracting fitting take-offs
- Run — the straight-line distance along the original pipe direction
- Roll Angle — how far to rotate the fitting from vertical
Assumes both end fittings are the same angle and that rise and roll are measured perpendicular to each other. Travel is center-to-center, so subtract one take-off for each fitting to get the cut length.
Angle Sum mode simply adds two fitting angles to get the combined bend:
- Angle A, Angle B — the individual fitting angles being stacked
This signed sum applies when both bends lie in the same plane. Use opposite signs for opposite directions. Rolling Offset mode handles its stated parallel-centerline geometry; neither mode solves arbitrary three-dimensional fitting rotations.
Reference Tables
Common fitting multipliers for the travel calculation. Multiply your true offset by the value below to get pipe travel.
| Fitting Angle | Travel Multiplier (1/sin) | Run Multiplier (1/tan) |
|---|---|---|
| 11.25° | 5.126 | 5.027 |
| 22.5° | 2.613 | 2.414 |
| 30° | 2.000 | 1.732 |
| 45° | 1.414 | 1.000 |
| 60° | 1.155 | 0.577 |
The following historical example take-offs are illustrative and are not tied to a verified fitting material, pattern or manufacturer. Do not use them for cutting; use the actual manufacturer’s center-to-end dimensions and engagement allowances:
| Pipe Size | 45° Take-Off (each end) | 90° Take-Off (each end) |
|---|---|---|
| 1/2″ | 1/4″ | 5/8″ |
| 3/4″ | 5/16″ | 3/4″ |
| 1″ | 3/8″ | 7/8″ |
| 1-1/2″ | 1/2″ | 1-1/8″ |
| 2″ | 5/8″ | 1-3/8″ |
Worked Example
You need to route around an obstacle that forces the pipe up 12 inches and over 8 inches, using 45° fittings on both ends.
- True offset = √(12² + 8²) = √208 = 14.42 in
- Travel = √208 / sin(45°) ≈ 20.3961 in (about 20.40 in)
- Roll the fitting atan(8 / 12) = 33.69° from vertical
- Subtract two take-offs from the unrounded 20.3961 in travel for your cut length
FAQ
What is a rolling offset?
A rolling offset happens when a pipe shifts both vertically and horizontally between two points. The pipe rolls around its axis as it offsets, hence the name.
Why can’t I use a 90° fitting in the calculator?
At 90°, this idealized geometry has zero run/advance and travel equal to the true offset. That limiting configuration is outside this tool’s supported 0° < angle < 90° range. It does not make 90° fittings physically impossible.
Is travel the same as the cut length?
No. Travel is center-to-center between fittings. Subtract the take-off (or lay-in) of each fitting to get the actual pipe cut length.
