Free online rolling offset / rolled offset / compound offset calculator for pipefitters. Computes travel length, run, set, advance length and true offset for any 3D pipe configuration that needs to skirt obstacles in both horizontal and vertical planes. Supports 11.25°, 22.5°, 30°, 45°, 60° and 90° fitting angles with their respective sine-reciprocal multipliers (1.414 for 45°, 2.000 for 30°, etc). Pipe sizes DN8 (1/4 inch) to DN1200 (48 inch). 3D visualization, weight calculation, center of gravity, bill of materials, PDF report export. Built by a pipefitter with 25 years of field experience.
This free online rolling offset calculator (also called rolled offset, pipe roll, or compound offset) gives you instantly the travel length T, the run R, the true offset c and the advance length A for any pipe configuration that needs to skirt an obstacle in 3D. It supports the common pipefitter angles — 45°, 22.5°, 30°, 60°, 11.25° — for pipe sizes from DN8 (1/4") up to DN1200 (48").
Unlike a one-shot number generator, this tool shows you an interactive 3D preview of the offset as you type, computes the pipe weight and center of gravity, and exports a PDF report with the full bill of materials — ready to hand to the shop or the cost estimator.
A rolling offset is a pipe configuration that changes direction in both the horizontal and vertical planes at the same time. It's how you connect two parallel pipelines that have been displaced sideways AND vertically — typically to skirt a beam, a tank or another existing pipe.
You build it with two equal-angle fittings (usually 45°), connected by a single straight piece of pipe — the travel. Geometrically, picture the pipe entering one corner of an imaginary 3D box and exiting at the opposite diagonal corner. The travel is the diagonal of the box.
The math has three steps. With H = horizontal offset (set/spread sideways) and V = vertical offset (rise/drop):
The famous 1.414 multiplier is just 1/sin(45°) rounded to three decimals. It's the field constant every pipefitter learns the first month on the job.
Same logic, different sine. Here are the multipliers you'll use most often:
| Fitting angle | Travel multiplier (1/sin θ) | Run multiplier (1/tan θ) | Use case |
|---|---|---|---|
| 11.25° | 5.126 | 5.027 | Very small deviation, long runs |
| 22.5° | 2.613 | 2.414 | Plumbing DWV, gentle bypass |
| 30° | 2.000 | 1.732 | HVAC ducting, mild offset |
| 45° | 1.414 | 1.000 | Most common in piping |
| 60° | 1.155 | 0.577 | Steep offset, low flow loss critical |
| 90° | 1.000 | 0.000 | Sharp turn (not really an "offset") |
A simple offset changes direction in ONE plane only — left/right OR up/down, not both. A rolling offset changes direction in BOTH planes simultaneously, so the connecting travel pipe is rotated (rolled) out of the original 2D plane. Quick test: if you can lay the whole assembly flat on a workbench and weld it without rotating, it's a simple offset. If the assembly has to be supported off the bench because the travel piece pokes upward, it's a rolling offset.
Because 1/sin(45°) = √2 ≈ 1.41421... and 45° elbows are by far the most common fitting in piping. The number is irrational (it's the square root of 2) but rounded to 1.414 it's accurate to better than 0.01% — good enough for any fabrication tolerance. Some pipefitter handbooks use 1.4142 for extra precision on long runs.
Yes — but the travel will be 2.613 × c instead of 1.414 × c, so the pipe is much longer (and the offset takes a lot more space along the run). 22.5° rolling offsets are mostly used in plumbing DWV (where flow direction changes need to be gentle) or in pipelines where pressure drop must be minimized. For most industrial piping, 45° is the right default.
The displayed travel T is the center-to-center distance between the two fittings. You still have to subtract the takeoff (face-to-face length of each elbow) before cutting your pipe. For a typical 45° butt-welded long-radius elbow, takeoff ≈ 1 × DN; for a short-radius elbow ≈ 0.625 × DN. The PDF report includes the takeoff values for the standard elbow types.
Yes — 100% free, no registration, no email, no watermark. All calculations run in your browser; nothing is sent to any server. You can print and export PDF reports without paying. The tool is built and maintained by a working pipefitter (25 years field experience) for the trade. If it saves you a trip back to the shop, share it with a colleague.
References: ASME B16.9 (Butt-welding fittings) · EN 10253 (European fittings) · Roger Wakefield, Advanced Plumbing (45° offset multiplier methods) · J. Triouleyre, Traçage en Chaudronnerie et Tuyauterie