How it works
An offset is two equal bends in opposite directions. The conduit runs diagonally between them, forming a right triangle whose short side is the offset height and whose angle is the bend angle. The diagonal length between the bend marks is the offset ÷ sin θ, so the multiplier is 1 ÷ sin θ: 2.0 at 30°, 1.414 at 45°.
The diagonal is longer than the straight run it replaces, so the conduit ends up shorter overall by the shrink: offset × tan(θ/2). Mark the bends that far apart and allow for the shrink when you measure the run.
Worked example
A 4 in offset made with two 30° bends:
- Multiplier = 1 ÷ sin 30° = 2
- Distance between bends = 4 in × 2 = 8 in
- Shrink = 4 in × tan(15°) = 1.072 in
| Input | Value |
|---|---|
| Offset height | 4 in |
| Bend angle | 30° |
| Result | Value |
|---|---|
| Distance between the two bend marks | 8 in |
| Multiplier | 2 × |
| Shrink (conduit length used up) | 1.072 in |
| Shrink per inch of offset | 0.268 in |
Assumptions and limits
- Exact trigonometric values. Trade rules of thumb round these; for example, 1/4 in of shrink per inch at 30°, where the exact value is 0.268 in.
- Distances are measured between the bend marks on the conduit, to the bender’s mark convention.
- The bender’s own gain, take-up, and springback are not included; test on a scrap piece.
Common questions
What is the multiplier for a 30 degree offset?
2.0. The distance between bends is twice the offset height.
What is the 45 degree multiplier?
1.414, the square root of 2.
What is shrink?
The conduit length used up by the offset. It is the offset times tan(half the bend angle); about 0.268 in per inch of offset at 30°.
Which bend angle should I use?
Small angles take more length but pull wire more easily; 45° is compact but harder on pulls. Pick by the space you have.
Sources
- Right-triangle geometry of an offset: spacing = offset ÷ sin θ (cosecant multiplier); shrink = offset × tan(θ ÷ 2).
- Common trade multipliers follow: 30° → 2.0, 45° → 1.414, 22.5° → 2.613, 10° → 5.76.
Updated 2026-09-30