Rolling Offset Calculator

Your details

The vertical distance the pipe must climb or drop between the two fitting centerlines.
in
The horizontal (side-to-side) distance between the two fitting centerlines.
in
The bend angle of each elbow fitting used. 45-degree elbows are the most common choice in commercial plumbing and HVAC.
The center-to-face dimension of each elbow fitting. Subtract twice this value from travel to get the spool piece cut length. Common values: 1/2" pipe ~ 0.75 in, 3/4" ~ 1.0 in, 1" ~ 1.25 in, 1.5" ~ 1.5 in, 2" ~ 2.0 in.
in
True offset
20in

Straight-line distance between the two fitting centerlines (Pythagorean diagonal of rise and roll).

Travel (center-to-center)28.284in
Run20in
Cut length25.284in
Travel multiplier1.4142
True Offset20
Travel28.284
Run20
Cut Length25.284

True offset: 20.000 | Travel: 28.284

  • The true offset (diagonal of rise and roll) is 20.000 units.
  • Travel center-to-center is 28.284 units. This is the dimension you measure between the fitting faces plus the two takeoffs.
  • The run advances 20.000 units along the main pipe direction.
  • After subtracting both fitting takeoffs, the spool piece cut length is 25.284 units.
  • With a travel multiplier of 1.4142, you can find travel for any true offset by multiplying: true offset times 1.4142.

Next stepMark the travel length on the pipe from center to center of the two fittings, then subtract twice the fitting takeoff to get the field cut mark.

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