Rolling Offset Calculator
Free pipefitter rolling offset calculator: true offset, travel and run for 45, 22.5, 30 and 60 degree fittings, with the multiplier shown.
What does the Rolling Offset Calculator do?
It solves a pipefitter rolling offset: given how far the pipe must rise and how far it must move sideways, it returns the true offset, the travel (the centre-to-centre length of pipe between the two fittings) and the run along each leg.
- Inputs: offset or rise, roll or horizontal movement, and the fitting angle.
- Output: travel, run and true offset, with the fitting multiplier.
- Method: Pythagorean combination of the two planes, then division by the sine and tangent of the fitting angle.
Quick answer
With a 10 inch offset, no roll and 45 degree fittings, the travel is 14.14 inches and the run is also about 14.14 inches. The familiar 45 degree multiplier of 1.414 is just 1 divided by the sine of 45 degrees.
What This Calculator Really Does
A rolling offset is a bend that moves a pipe in two directions at once: up or down (the offset) and left or right (the roll). Because the two movements happen in different planes, they do not simply add up. Instead you combine them as the two legs of a right triangle to get the true offset, which is the actual straight-line distance the pipe must travel in space. Once you have the true offset, the fittings determine how much pipe length that represents. The angle of the fittings sets a fixed multiplier, and the travel is the true offset multiplied by it. The same geometry gives the run, the distance from the fitting back to where the offset begins.
The rules it applies
- True offset: the square root of the offset squared plus the roll squared.
- Travel: true offset divided by the sine of the fitting angle, which equals the true offset times the standard multiplier.
- Run: true offset divided by the tangent of the fitting angle.
- Multipliers: 45 degrees gives 1.414, 22.5 gives 2.613, 30 gives 2.000, and 60 gives 1.155.
- Not modelled: fitting takeout, weld gaps and the wall thickness of the pipe itself.
Worked example with real numbers
Offset 10 inches, roll 0 inches, 45 degree fittings. True offset = the square root of (100 + 0) = 10 inches. Travel = 10 / sin(45) = 10 x 1.414 = 14.14 inches, and the run is also 14.14 inches because tangent and sine are equal at 45 degrees. If you then rolled the same joint 10 inches sideways, the true offset would become 14.14 and the travel would rise to 20 inches.
Reading the result
The travel is the length along the sloped section of pipe; the run is how far the bend reaches along each straight leg. On the job you measure centre to centre and then subtract the fitting takeout to find the cut length, so pair this result with the pipe cutback figure for the fittings you are using. Steeper fittings shrink the travel but increase the force the offset puts on the anchors, so 22.5 degree fittings are used when space allows and 60 degree only in tight corners.
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Frequently Asked Questions
How is the travel length in a rolling offset calculated?
Combine the offset and the roll as a right triangle to get the true offset, then divide by the sine of the fitting angle to get the travel and by the tangent to get the run. The steps panel shows each figure.
What do I need to use the Rolling Offset Calculator?
The offset or rise, the roll or horizontal movement, and the fitting angle. The standard 45, 22.5, 30 and 60 degree multipliers are built in.
What does the result from the Rolling Offset Calculator show?
The travel (centre-to-centre pipe length), the run along each leg, and the true offset that combines both planes.
What is the multiplier for a 45 degree offset?
About 1.414. It is 1 divided by the sine of 45 degrees, and it converts a true offset into the travel length of the sloped pipe.
Is the Rolling Offset Calculator really free?
Yes — 100 percent free, no sign-up, and everything runs in your browser.
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