Conduit Bending
Offset multipliers, shrinkage values, stub-up deducts, and common bend types.
6 reference items · 3 sections
Offset Bend Multipliers
Offset Multipliers & Shrinkage
Offset Bend Multipliers
| Bend Angle | Multiplier | Shrinkage per inch of offset |
|---|---|---|
| 10° | 6.0 | 1/16" (0.0625") |
| 22.5° | 2.6 | 3/16" (0.1875") |
| 30° | 2.0 | 1/4" (0.25") |
| 45° | 1.414 | 3/8" (0.375") |
| 60° | 1.155 | 1/2" (0.5") |
1.Multiplier = 1 / sin(angle)
2.Distance between bends = Offset depth × Multiplier
How to Use
1. Determine the offset depth needed (inches)
2. Choose your bend angle
3. Distance between marks = Depth × Multiplier
4. Subtract shrinkage from your starting measurement
Example: 4" offset at 30° → Distance between bends = 4 × 2.0 = 8". Shrinkage = 4 × ¼" = 1". Start first mark 1" closer to the end.
Shrinkage & Gain
90° Stub-Up: Take-Up & Gain
90° Stub-Up Deduct (Take-Up) Values
| Conduit Size | Deduct | Gain | Radius |
|---|---|---|---|
| ½" EMT | 5" | 3" | 4" |
| ¾" EMT | 6" | 3½" | 4½" |
| 1" EMT | 8" | 4½" | 5¾" |
| 1¼" EMT | 11" | 5½" | 7¼" |
| 1½" EMT | 11" | 6" | 8¼" |
| 2" EMT | 11" | 6½" | 9½" |
1.Deduct = amount subtracted from stub height to find mark placement
2.Gain = difference between actual stub and calculated stub
3.These values vary slightly by bender manufacturer
Stub-Up Procedure
1. Determine desired stub height
2. Subtract the deduct value for your conduit size
3. Mark the conduit at that distance from the end
4. Place mark at the bender's arrow/notch
5. Bend to 90°
Common Bend Types
Back-to-Back 90° Bends
Used to create a U-shape or route conduit between two points at different heights.
Procedure
1. Make the first 90° stub-up to desired height
2. Measure from the back of the first bend to where the second bend should start
3. Place that mark at the bender's back-of-bend mark (star/notch)
4. Bend the second 90° in the opposite direction
The back of the bend is the point where the conduit first touches the floor/surface when the stub is standing upright.
3-Point Saddle Bend
Used to navigate around obstacles (pipes, other conduit) while keeping the conduit run straight.
3-Point Saddle: Center Bend & Outer Bends
| Center Angle | Outer Angles | Multiplier (depth to 1st mark) |
|---|---|---|
| 22° | 11° | 2.5 |
| 30° | 15° | 2.0 |
| 45° | 22.5° | 1.414 |
| 60° | 30° | 1.155 |
1.Mark center of obstacle on conduit
2.Outer marks = Obstacle depth × Multiplier, equally spaced from center
3.Shrinkage: multiply obstacle depth by shrinkage factor for outer angle
4-Point Saddle Bend
A 4-point saddle consists of two identical offsets that create a raised section to clear an obstruction.
Procedure
1. Determine the obstacle height and width
2. Make two offset bends (same angle) spaced the width of the obstacle apart
3. Each offset depth = obstacle height
4. Use offset multiplier table for mark spacing
Shrinkage for a 4-point saddle is double the shrinkage of a single offset (since you have two offsets).
Segment (Concentric) Bending
Used for large-radius bends or when multiple conduits must follow the same curve at different radii.
Developed Length Formula
DL = (Radius × Angle × π) ÷ 180
Developed Length of a Bend
| Variable | Description | Unit |
|---|---|---|
| DL | Developed length | inches |
| Radius | Centerline radius | inches |
| Angle | Total bend angle | degrees |
Divide the total bend into equal segments (typically 5°-15° each). Each segment is a small bend applied at evenly spaced marks along the developed length.
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