Rolling Offset Calculator
Calculate a pipe rolling offset from set and roll, including true offset, travel, run/advance, roll angle, travel multiplier, and cut length after fitting takeouts.
Enter the vertical set, horizontal roll, and fitting angle to calculate the true rolling offset, center-to-center travel, advance/run, roll angle, and optional cut length.
Rolling offset dimensions
Use one consistent length unit throughout (for example, inches or millimetres). True offset = √(set² + roll²). Travel = true offset ÷ sin(angle). Run = true offset ÷ tan(angle). Cut length subtracts the two entered fitting takeouts from center-to-center travel.
Rolling Offset Calculator for Pipe Fitting
This rolling offset calculator solves the three-dimensional geometry created when a pipe must change elevation and move sideways at the same time. Enter the vertical set (or rise), horizontal roll, and fitting angle. The calculator returns the true offset, center-to-center travel, run or advance, roll orientation angle, fitting multipliers, and an optional cut length after fitting takeouts.
The calculator is unit-neutral: if set, roll, and takeouts are entered in inches, the length results are inches. If they are entered in millimetres, the length results are millimetres. Do not mix units in the same calculation.
Rolling Offset Formula
A rolling offset is solved in two right-triangle steps. First combine the two perpendicular offsets:
True offset = √(set² + roll²)
Then apply the selected fitting angle θ:
Travel = true offset ÷ sin(θ)
Run = true offset ÷ tan(θ)
Travel is the diagonal center-to-center distance between the fittings. Run (also called advance) is the distance consumed along the original pipe direction.
45 Degree Rolling Offset Calculator
For a 45 degree rolling offset calculator, sin 45° is √2/2 and tan 45° is 1. The equations simplify to:
Travel = true offset × 1.41421356
Run = true offset
Example: a 3-inch set and 4-inch roll create a 5-inch true offset. With 45° fittings, center-to-center travel is about 7.071 inches and run is 5 inches.
Pipe Rolling Offset Calculator: Set, Roll, Travel and Run
Pipefitters use several names for the same geometry. Set or rise is the vertical displacement. Roll is the lateral displacement. True offset is the diagonal across those two perpendicular displacements. Travel is the center-to-center sloping piece between fittings. Run or advance is the axial distance used to make the offset.
Keeping these values separate matters. Multiplying only the vertical set by 1.414 in a rolling offset is wrong when a lateral roll is also present; the 45° multiplier must be applied to the combined true offset.
Roll Orientation Angle
The calculator also reports the orientation of the roll in the set/roll plane:
Roll angle = atan2(roll, set)
This angle helps describe how the offset is rotated around the pipe axis. A 3-by-4 set/roll has an orientation angle of about 53.13° measured from the set axis toward the roll axis.
Cut Length and Fitting Takeout
The trigonometric travel is a center-to-center measurement. It is not automatically the physical end-to-end cut length of the straight pipe between two fittings. If you know the center-to-end or center-to-face takeout for each actual fitting, enter both values:
Cut length = travel − takeout A − takeout B
Takeout depends on fitting type, pipe size, schedule, joining method, and manufacturer. The calculator intentionally does not guess these dimensions. Use the fitting manufacturer’s dimensional data or an approved shop reference.
Common Rolling Offset Multipliers
- 11.25°: travel multiplier ≈ 5.126; run multiplier ≈ 5.027.
- 22.5°: travel multiplier ≈ 2.613; run multiplier ≈ 2.414.
- 30°: travel multiplier = 2.000; run multiplier ≈ 1.732.
- 45°: travel multiplier ≈ 1.414; run multiplier = 1.000.
- 60°: travel multiplier ≈ 1.155; run multiplier ≈ 0.577.
The calculator computes the trigonometry directly, and the custom-angle option is not limited to the rounded shop multipliers above.
Frequently Asked Questions
How do I calculate a rolling offset with 45 degree fittings?
Square the set and roll, add them, and take the square root to find the true offset. Multiply that true offset by 1.41421356 for center-to-center travel. For 45° fittings, the run equals the true offset.
Is travel the same as pipe cut length?
No. Travel is normally the fitting-center to fitting-center distance. To estimate straight pipe cut length, subtract the actual takeout of both fittings. Verify takeouts from manufacturer or approved fabrication data.
What if one side of the rolling offset is zero?
The calculator still works. A zero set or zero roll reduces the geometry to a simple offset in one plane, while the travel and run formulas remain the same.
Can I use millimetres?
Yes. Use millimetres consistently for set, roll, and takeouts, and all length results will be in millimetres. Angles are always entered in degrees.
Methodology
SeriesCalculator compared current pipe-offset and rolling-offset tools and found a consistent trade-math pattern: combine set and roll with the Pythagorean theorem, then calculate travel with the sine relationship and run with the tangent relationship. Several strong competitors also subtract fitting takeouts and expose the 45° 1.414 multiplier. Our implementation adds the roll orientation angle and supports a custom fitting angle while keeping takeout separate from the geometric center-to-center travel.
This calculator is a geometry and layout aid, not a substitute for approved piping drawings, welding procedures, code requirements, fitting dimensions, slope requirements, fabrication tolerances, or field verification.