What the calculator gives you
- True offset: the diagonal across the rise and roll.
- Distance between bends: true offset times the multiplier.
- Total shrink: the length the conduit loses in the two bends.
- Bend plane tilt: how far the plane of both bends leans from the rise direction.
Steps for a rolling offset
- Measure the rise and the roll from center line to center line.
- Enter them and pick the bender angle.
- Mark bend 1. Add the shrink to your overall length.
- Mark bend 2 the distance between bends from the first mark.
- Make bend 1 with the plane at the tilt shown.
- Turn the conduit 180 degrees and make bend 2 on its mark.
Dry fit the piece and check it against the job before you cut the run.
Multiplier and shrink by angle
| Bend angle | Multiplier (1 / sin) | Shrink per inch of offset | Run factor (1 / tan) |
|---|---|---|---|
| 5° | 11.474 | 0.044 in | 11.430 |
| 10° | 5.759 | 0.087 in | 5.671 |
| 11.25° | 5.126 | 0.098 in | 5.027 |
| 22.5° | 2.613 | 0.199 in | 2.414 |
| 30° | 2.000 | 0.268 in | 1.732 |
| 45° | 1.414 | 0.414 in | 1.000 |
| 60° | 1.155 | 0.577 in | 0.577 |
Distance between bends
Find your true offset in the left column, then read across to your bend angle.
| True offset | 10° | 22.5° | 30° | 45° | 60° |
|---|---|---|---|---|---|
| 2" | 11.52 | 5.23 | 4.00 | 2.83 | 2.31 |
| 4" | 23.04 | 10.45 | 8.00 | 5.66 | 4.62 |
| 6" | 34.55 | 15.68 | 12.00 | 8.49 | 6.93 |
| 8" | 46.07 | 20.91 | 16.00 | 11.31 | 9.24 |
| 10" | 57.59 | 26.13 | 20.00 | 14.14 | 11.55 |
| 12" | 69.11 | 31.36 | 24.00 | 16.97 | 13.86 |
| 15" | 86.38 | 39.20 | 30.00 | 21.21 | 17.32 |
| 18" | 103.66 | 47.04 | 36.00 | 25.46 | 20.78 |
| 24" | 138.21 | 62.72 | 48.00 | 33.94 | 27.71 |
Questions
What bend angle should I use for a rolling offset?
Use 30 degrees for most work. It has a multiplier of exactly 2. Use 45 degrees when the offset must be short, and 22.5 degrees for a long, gentle offset.
What is shrink?
Shrink is the length the conduit run loses when you bend an offset into it. It equals the true offset times the tangent of half the bend angle. Add it to your overall length before you cut.
Do I need a first mark?
No. Enter the first mark from the end of the conduit, and the tool gives you the second mark.