Free study tools · Trade math
Pipe Offset Calculator: Travel and Run
Enter how far the pipe has to move over, pick your fittings, and get the travel (center-to-center length of the angled piece) and the run (how far along the line the offset takes). Works for simple offsets and rolling offsets, with the constant and the formula shown.
1. The offset
2. Result
The constants
| Fitting | Travel = offset × | Run = offset × |
|---|---|---|
| 45° | 1.414 | 1.000 |
| 60° | 1.155 | 0.577 |
| 22-1/2° | 2.613 | 2.414 |
| 11-1/4° | 5.126 | 5.027 |
Where they come from: the offset, run and travel form a right triangle. Travel = offset ÷ sin(angle) and run = offset ÷ tan(angle) (offset × the cotangent). For 45°, 1 ÷ sin 45° = 1.414, and the run equals the offset.
Rolling offsets move in two directions at once. Square the rise and the roll, add them, and take the square root to get the true offset. Then use the true offset in the same formulas.
Travel and run are center-to-center. To get the pipe length to cut, subtract the fitting allowance (take-off) for both fittings, which depends on the fitting you're using.
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Study aid — confirm with the current 248 CMR and your inspector. This is geometry, not a code requirement. Measure twice and check fitting take-offs with the manufacturer before cutting. PressureTest is independent and not affiliated with the Commonwealth of Massachusetts, the Board of State Examiners of Plumbers & Gas Fitters or PSI.