Segment Bend Calculator

A segmented conduit bend uses multiple small, equal bends to form a smooth directional change where a standard one-shot, 45-degree, or 90-degree bend does not produce the required radius. The Segment Bend Calculator establishes two layout numbers used directly on the conduit before bending:

• Angle per bend — the amount of bend applied at each mark.
• Spacing between marks — the developed distance between adjacent segment marks.

It also calculates the developed mark span and the final segment-mark location from the conduit end. These measurements support repeatable conduit layout for large-radius offsets, sweeps, and directional changes where raceway appearance, conductor pulling conditions, or physical clearance require a gradual bend.

Segment Bend Layout Inputs

The calculator uses four field measurements or layout decisions.

Input	Electrical layout purpose
Total bend angle	The full change in conduit direction required, in degrees
Number of bend marks/shots	The number of equal segment marks to make on the conduit
Bend radius	The target centerline radius of the completed segmented bend
First mark from conduit end	The distance from the conduit end to the first bend mark

Number of bend marks/shots is the count of actual marks, not the number of open spaces between marks. The calculator treats the first and last marks as the ends of the developed layout span. Therefore, (N) marks create (N – 1) spacing intervals.

For example, six marked bend locations create five equal spaces between the first and last mark.

Segment Bend Geometry

The calculator first divides the total direction change equally across the selected number of bend marks:

\(\text{Angle per bend} = \frac{\text{Total bend angle}}{\text{Number of bend marks/shots}}\)

It then calculates the arc length along the desired centerline radius:

\(\text{Developed mark span} = R \times \theta\)

Where:

• (R) = Bend radius
• \(\theta\) = total bend angle expressed in radians

The developed span is divided by the number of spacing intervals:

\(\text{Spacing between marks} = \frac{\text{Developed mark span}} {\text{Number of bend marks/shots} - 1}\)

Finally, the calculator locates the last mark:

\(\text{Last segment mark from conduit end} = \text{First mark from conduit end} + \text{Developed mark span}\)

The spacing is measured along the straight, unbent conduit before each shot is made. It is not a chord measurement taken across the completed curve.

Calculation Example

A conduit run requires a 90-degree segmented bend with a 24-inch target centerline radius. The layout begins 24 inches from the conduit end and uses six equal bend marks.

Input	Value
Total bend angle	90 deg
Number of bend marks/shots	6
Bend radius	24 in
First mark from conduit end	24 in

Results

Result	Value
Angle per bend	15 deg
Spacing intervals	5
Spacing between marks	7.5398 in
Developed mark span	37.6991 in
Last segment mark from conduit end	61.6991 in
Bend count	6

The layout marks are placed at the following distances from the conduit end:

Mark	Distance from conduit end
First segment mark	24.0000 in
Second segment mark	31.5398 in
Third segment mark	39.0796 in
Fourth segment mark	46.6194 in
Fifth segment mark	54.1592 in
Last segment mark	61.6991 in

Make six 15-degree shots at these marks, maintaining the intended bend orientation throughout the sequence. The completed conduit develops a 90-degree directional change over the calculated 24-inch centerline radius.

Conduit Layout Use

Segment-bend calculations are most useful when a raceway must follow a controlled curve rather than make a sharp directional change. Common layout applications include:

• Large-radius conduit turns where physical routing does not accommodate a standard factory or hand-bent elbow.
• Parallel raceways that must maintain consistent spacing and appearance through a directional transition.
• Conduit pathways where a gradual change may improve conductor installation conditions compared with a tighter bend.
• Custom fabricated transitions between equipment, pull points, cable tray interfaces, or structural obstructions.

The First mark from conduit end establishes where the segmented geometry begins. That location must be coordinated with couplings, connectors, enclosure entries, support locations, other bends, and the available straight conduit length. A mathematically correct segment layout can still fail in the field if the first mark is positioned where the bender, conduit coupling, or adjacent raceway prevents the required shot.

Field Verification

The calculated values define an ideal centerline geometry. Actual results depend on conduit type, nominal trade size, bender method, material springback, and the consistency of each individual shot.

Mark each spacing interval from the same reference end of the conduit. Keep the conduit indexed so every bend occurs in the same plane. A small rotation error between shots creates corkscrew rather than planar bend geometry.

The target Bend radius is a centerline radius. Verify the finished conduit against the required physical clearance, outside-radius clearance, and equipment-entry alignment rather than relying only on the marked span.

Code and installation acceptance remain separate from this geometry calculation. Confirm the completed raceway installation satisfies the applicable bend, pulling, support, accessibility, conductor-installation, and project requirements enforced by the AHJ.