Electrical Conduit Offset Calculator
For EMT, Rigid, and IMC Bending
10° (Multiplier 6)
22.5° (Multiplier 2.6)
30° (Multiplier 2.0)
45° (Multiplier 1.41)
60° (Multiplier 1.15)
Where you want the offset to align.
Bending Layout
Distance Between Bends (Travel):
0″
Total Shrinkage:
0″
First Mark (Arrow):
0″
Second Mark:
0″
Tech Note: Calculations assume standard industry multipliers. Values are rounded to the nearest 1/16th of an inch.
How to Calculate Conduit Offsets
Bending electrical conduit (EMT, IMC, or Rigid) requires precision to ensure the pipe fits snugly against obstructions without placing stress on the run. The Offset is the most common bend an electrician performs, used to route conduit around an obstacle or to change elevation to enter a box.
The Multiplier Formula
To bend a perfect offset, you need two pieces of information: the height of the obstruction (Offset Depth) and the angle you intend to bend. The formula determines the distance between your two bending marks:
Distance Between Bends = Offset Depth × Cosecant(Angle)
Electricians rarely calculate the cosecant in the field. Instead, they use standard "Multipliers" based on common angles:
| Bend Angle | Multiplier | Shrink per Inch of Offset |
|---|---|---|
| 10° | 6.0 | 1/16″ |
| 22.5° | 2.6 | 3/16″ |
| 30° | 2.0 | 1/4″ |
| 45° | 1.41 | 3/8″ |
| 60° | 1.15 | 1/2″ |
Understanding Shrinkage
When you bend an offset, the overall length of the conduit effectively "shrinks" because the pipe is traveling diagonally rather than in a straight line. If you do not account for shrinkage, your conduit will come up short of the target box.
Total Shrink = Offset Depth × Shrink Constant
For example, using a 30° bend on a 6-inch offset: The shrink constant is 1/4″ per inch. Therefore, 6″ × 0.25 = 1.5″ of total shrink. You must add this 1.5″ to your measurement when marking the first bend to ensure the pipe ends up where you measured it.
Step-by-Step Bending Guide
- Measure: Determine the distance from the end of the conduit (or coupling) to the obstruction.
- Determine Height: Measure the height of the obstruction (the Offset Depth).
- Calculate Shrink: Multiply the depth by the shrink constant for your chosen angle. Add this to your first measurement to find your First Mark.
- Calculate Travel: Multiply the depth by the angle multiplier (e.g., 2.0 for 30°) to find the distance to your Second Mark.
- Bend: Place the bender arrow on the first mark and bend to the chosen angle. Slide the pipe forward, align the second mark with the arrow (or star/notch depending on bender type), and bend to the same angle in the opposite direction (rotate pipe 180°).