Bend Multiplier Calculator
Key Takeaways
- The multiplier converts offset depth to travel distance between bends
- Shrink compensates for the conduit length lost in a bend
- 30 degrees is the most common angle with a simple 2x multiplier
Contents
What Is a Bend Multiplier?
A bend multiplier is a constant used in conduit bending to convert an offset depth into the travel distance between two bends. It is derived from trigonometry: the multiplier equals 1 divided by the sine of the bend angle. For a 30-degree offset, sin(30) = 0.5, so the multiplier is 2.0.
The shrink per inch value tells you how much the conduit's effective straight-line length is reduced for each inch of offset depth. You need to account for shrink when marking your conduit so the endpoint lands where you intended.
Multiplier = 1 / sin(bend angle)
Multiplier and Shrink Reference Table
The following table lists the standard bend angles used in conduit work along with their multipliers and shrink values:
| Bend Angle | Multiplier | Shrink Per Inch | Shrink Fraction |
|---|---|---|---|
| 10° | 5.759 | 0.0625 | 1/16" |
| 22.5° | 2.613 | 0.1875 | 3/16" |
| 30° | 2.000 | 0.2500 | 1/4" |
| 45° | 1.414 | 0.3750 | 3/8" |
| 60° | 1.155 | 0.5000 | 1/2" |
How to Use the Multiplier
To calculate the travel distance for an offset bend, multiply the offset depth by the multiplier for your chosen angle. Then calculate the shrink by multiplying the offset depth by the shrink per inch value.
Example: 6" Offset at 30 Degrees
- Offset depth: 6 inches
- Multiplier (30°): 2.000
- Travel: 6 x 2.000 = 12 inches between bends
- Shrink: 6 x 1/4 = 1-1/2 inches
Frequently Asked Questions
What is a bend multiplier in conduit bending?
A bend multiplier is a number you multiply by the offset depth to find the distance between bends (travel). It is calculated as 1 divided by the sine of the bend angle. For example, a 30-degree bend has a multiplier of 2.0, so a 6-inch offset requires 12 inches of travel between bends.
What is shrink per inch and why does it matter?
Shrink per inch is the amount of conduit length lost per inch of offset depth when making a bend. It accounts for the fact that the conduit path through an offset is longer than a straight run. You must add the shrink to your first mark to keep the stub or endpoint at the correct position.
Which bend angle should I use for conduit offsets?
The most common angle for conduit offsets is 30 degrees because it has a simple multiplier of 2x and a manageable shrink of 1/4 inch per inch. For shallow offsets, 10 or 22.5 degrees work well. For tight spaces, 45 or 60 degrees produce a shorter travel distance but more shrink.