Compound Pipe Angle Calculator

Calculate pipe travel length, true offset, and run from rise, roll, and fitting angle, or add compound angles in degrees or radians.

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Compound Pipe Angle Formula

The calculator uses two formulas depending on the mode you pick.

Rolling Offset mode finds the pipe length (travel) between two fittings when the offset goes both up and sideways:

True Offset = √(Rise² + Roll²)
Travel = True Offset / sin(Fitting Angle)
Run = True Offset / tan(Fitting Angle)
Roll Angle = atan(Roll / Rise)

• Rise — vertical offset between the two pipe centerlines
• Roll — horizontal offset between the two pipe centerlines
• True Offset — the diagonal offset the pipe actually spans
• Fitting Angle — the angle of the fittings on each end (45°, 22.5°, etc.)
• Travel — the center-to-center pipe length you cut
• Run — the straight-line distance along the original pipe direction
• Roll Angle — how far to rotate the fitting from vertical

Assumes both end fittings are the same angle and that rise and roll are measured perpendicular to each other. Travel is center-to-center, so subtract fitting take-off to get the cut length.

Angle Sum mode simply adds two fitting angles to get the combined bend:

Compound Angle = Angle A + Angle B

• Angle A, Angle B — the individual fitting angles being stacked

This applies when both bends lie in the same plane. If the second fitting is rotated out of plane, use Rolling Offset mode instead.

Reference Tables

Common fitting multipliers for the travel calculation. Multiply your true offset by the value below to get pipe travel.

Typical fitting take-offs to subtract from travel for a clean cut length (varies by manufacturer; verify against your spec sheet):

Worked Example

You need to route around an obstacle that forces the pipe up 12 inches and over 8 inches, using 45° fittings on both ends.

1. True offset = √(12² + 8²) = √208 = 14.42 in
2. Travel = 14.42 / sin(45°) = 14.42 × 1.414 = 20.39 in
3. Roll the fitting atan(8 / 12) = 33.69° from vertical
4. Subtract two take-offs from 20.39 in for your cut length

FAQ

What is a rolling offset?
A rolling offset happens when a pipe shifts both vertically and horizontally between two points. The pipe rolls around its axis as it offsets, hence the name.

Why can’t I use a 90° fitting in the calculator?
The travel formula divides by sin of the fitting angle. At 90° the math still works, but you no longer have an offset path; the pipe just turns the corner. The calculator restricts input to angles between 0° and 90° where the rolling offset method applies.

Is travel the same as the cut length?
No. Travel is center-to-center between fittings. Subtract the take-off (or lay-in) of each fitting to get the actual pipe cut length.