Rolling Offset Calculator
Calculate the travel piece for a rolling pipe offset from the roll, rise and fitting angle.
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What this tool does
Calculate the travel piece for a rolling pipe offset from the roll, rise and fitting angle. Centre-to-centre dimensions: subtract the fitting take-offs (socket depths) for your fitting type to get the cut length. The roll angle tells you how far to rotate the second fitting.
How to use the Rolling Offset Calculator
- Enter or select roll (horizontal offset) in in.
- Enter or select rise (vertical offset) in in.
- Enter or select fitting angle.
- Read the calculated result; change any measurement to compare alternatives.
Formula
true offset = √(roll² + rise²); travel = true offset / sin(fitting angle); run = √(travel² − true offset²); bend angle of the roll = atan(roll / rise)
- roll
- Roll (horizontal offset) (in, before metric conversion)
- riseOff
- Rise (vertical offset) (in, before metric conversion)
- fitting
- Fitting angle
Centre-to-centre dimensions: subtract the fitting take-offs (socket depths) for your fitting type to get the cut length. The roll angle tells you how far to rotate the second fitting.
Worked example
For rolling offset calculator, the following measurements illustrate the exact method: Roll (horizontal offset): 12; Rise (vertical offset): 12; Fitting angle: 45.
Inputs
- Roll (horizontal offset)12 in
- Rise (vertical offset)12 in
- Fitting angle45°
Result
- Travel (centre-to-centre)24 in
- True offset16.97 in
- Run / advance16.97 in
- Roll angle (degrees)45
Results explained
- Travel (centre-to-centre)
- Travel (centre-to-centre) from the formula above, expressed in in before metric conversion. Centre-to-centre dimensions: subtract the fitting take-offs (socket depths) for your fitting type to get the cut length. The roll angle tells you how far to rotate the second fitting.
- True offset
- True offset from the formula above, expressed in in before metric conversion. Centre-to-centre dimensions: subtract the fitting take-offs (socket depths) for your fitting type to get the cut length. The roll angle tells you how far to rotate the second fitting.
- Run / advance
- Run / advance from the formula above, expressed in in before metric conversion. Centre-to-centre dimensions: subtract the fitting take-offs (socket depths) for your fitting type to get the cut length. The roll angle tells you how far to rotate the second fitting.
- Roll angle (degrees)
- Roll angle (degrees) from the formula above. Centre-to-centre dimensions: subtract the fitting take-offs (socket depths) for your fitting type to get the cut length. The roll angle tells you how far to rotate the second fitting.
Frequently asked questions
An offset that moves in two planes at once — sideways (roll) and up or down (rise). Combining them gives a single 'true offset' that the angled travel piece must cross.
True offset = √(roll² + rise²); with 45° fittings, travel = true offset × 1.414 and run = true offset. Two 12 in legs give a 17 in true offset and a 24 in travel piece.
Travel is the angled centre-to-centre piece you cut (minus take-offs); run (advance) is how far forward the pipe progresses while making the offset.
Cut length = travel − the take-offs of both fittings (the depth each pipe end disappears into its fitting). Take-offs come from the fitting manufacturer's table.
It is the angle between the rise direction and the true-offset plane — you rotate the offset fittings by this angle so the travel piece lines up in 3D.