Free calculator

Rolling offset calculator: rise, roll, travel, and cut length

Type the rise and the roll, then pick a fitting angle or give the setback you have room for. You get the true offset, the travel, the run, and the cut length with take-outs and gaps off, drawn as the box the pipe runs through.

Runs in your browser. Nothing you type is stored or sent. Take-outs are the commonly published butt-weld values from the take-out chart: default values, check your fittings.

How this rolling offset calculator works

True offset = √(rise² + roll²)
Travel      = true offset ÷ sin(angle)
Run         = true offset ÷ tan(angle)
Cut         = travel − 2 × take-out − 2 × gap

With a setback instead of an angle, the run is fixed and the angle follows:

Travel = √(true offset² + setback²)
Angle  = atan(true offset ÷ setback)

The fittings at that angle are 90s cut down to it, with a take-out of the 90's center-to-end × tan(angle ÷ 2). The full method, including how to measure the rise and roll and how far to roll the fittings, is in the rolling offset formula guide.

Check it against a known answer

Rise 8, roll 16, 45 degrees, 2 inch 45 LR, 1/8 gap: true offset 17 7/8, travel 25 5/16, run 17 7/8, cut 22 5/16.
Rise 12, roll 16, 45 degrees, no fittings: true offset 20, travel 28 5/16, run 20.
Rise 3, roll 4, setback 12, no fittings: true offset 5, travel 13, angle 22.62 degrees.

For an offset in one plane, use the pipe offset calculator.