Conduit Bending Multipliers and Marking Guide
Look up common offset multipliers and shrink allowances, identify bender marks, and print a compact field reference before laying out a bend.
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Offset multiplier chart
For a two-bend offset, the multiplier relates offset rise to spacing between the two bend marks. Shrink is the approximate loss of forward reach introduced by the offset. These are rounded field factors from the Klein guide, not precision fabrication tolerances.
| Bend angle | Rise-to-spacing multiplier | Approximate shrink per inch of rise |
|---|---|---|
| 10° | 6.0 | 1/16 in. |
| 22.5° | 2.6 | 3/16 in. |
| 30° | 2.0 | 1/4 in. |
| 45° | 1.4 | 3/8 in. |
| 60° | 1.2 | 1/2 in. |
The units cancel in the rise-to-spacing multiplier: rise and spacing must use the same length unit. The shrink column is written in inches per inch of rise. Do not add an offset multiplier to a bender take-up deduction; they describe different dimensions.
These factors apply to a pair of equal, opposing bends in one plane. A rolling offset, saddle, back-to-back bend, or segmented bend needs its own layout. Use the existing conduit bend tools for project-specific marks.
Download the offset factor chart (CSV)
Five common angles with rounded spacing multipliers and shrink allowances. Verify the factors against your bender instructions.
Bender marks
| Mark / term | Typical purpose | What remains model-specific |
|---|---|---|
| Arrow | Alignment for a stub-up or offset bend mark | Check which end and edge the instructions use. |
| Star | Reference for a back-of-90 / back-to-back bend | Do not substitute it for the arrow without changing the layout method. |
| Rim notch / saddle reference | Center reference for the applicable saddle method | The guide may specify a particular center bend angle. |
| Degree scale | An angle reference during bending | Springback, reading position, and operating instructions remain separate. |
| Take-up / deduct | A bender-specific allowance used for a stub-up | Depends on the shoe, trade size, and conduit; it is not a universal number. |
| Gain | Difference between two straight layout legs and a developed bend | Not the same quantity as shrink or take-up. |
Field layout checks
- Identify the bender shoe and the raceway material and trade size. Confirm that the combination is permitted by the tool instructions.
- Choose the bend family and angle before applying a multiplier. Record whether a mark references the near end, far end, center, or back of a bend.
- Keep the bend plane and mark orientation consistent. A correct spacing does not prevent a dogleg.
- Check the result against the actual route and fittings before repeating a layout on more material.
For example, the 30° row says to use the 2.0 spacing factor and the corresponding rounded shrink allowance; it does not identify the correct offset height for an installation or the proper take-up of a particular shoe.
Print this page for a reference copy. The full manufacturer guide remains necessary for operating technique, conduit capacity, and exact marking conventions. Compare tube dimensions separately in the conduit dimension tables.