Rolling offset calculator

Enter the rise and the roll between two parallel pipes and the angle of the two fittings. The tool gives the true offset, the travel, the run, the roll angle and the cut length after the fitting take-outs. It runs in your browser. Nothing you enter is sent anywhere.

This calculator needs JavaScript. It runs fully in your browser and sends nothing to a server. The formulas and sources are on the methodology page.

1. Offset

Rise and roll

Rise (set), in. Vertical distance between the centre lines of the two pipes. Enter 0 for an offset that lies flat.

Roll, in. Horizontal distance between the centre lines. Enter 0 for a plain offset with no roll.

Unit Rise, roll, take-outs and results are all in this unit. A rise or roll above 10,000 is not accepted, nor a travel above 100,000 (an angle typed as a fraction of a degree); those limits are typing error guards of this tool.

2. Fittings

Fitting angle

Angle (degrees) Both fittings have this angle. Use the buttons or type any angle above 0 and up to 90.

Take-out

The take-out is the fitting's laying length: from the centre of the fitting to the bottom of the socket, where the pipe end stops. It is subtracted from the travel at each end to give the length of pipe to cut.

None. The cut length equals the travel, centre to centre of the fittings. From the table. Catalog laying lengths of one brand of wrot copper elbow and one brand of PVC Schedule 40 and Schedule 80 elbow, 45 and 90 degrees. The angle follows the fitting. Typed in. Measured from your fitting, or from the catalog of your brand. Use this for threaded, press, PEX, cast and DWV fittings, for 22.5 and 60 degree fittings, and for every other brand.

Result

What this tool does not do

Bent pipe and bend radius. The tool is for two fittings joined by a straight piece.
Offsets between pipes that are not parallel, and fittings of two different angles.
Take-outs for threaded, press, PEX, cast copper and DWV fittings, for 22.5 and 60 degree fittings, and for any brand other than the two in the table. Type those in from the fitting in hand or from its catalog.
Thread makeup, and any allowance for a solder or cement gap at the bottom of the socket.

The formulas, the catalog pages the take-outs come from and the open questions are on the methodology page. Sources were last checked on October 4, 2026.