Concentric Bend Calculator
Use this concentric bend workflow to space parallel conduit bends from an inside radius, conduit spacing, bend angle, and segment count.
- Target centerline radius
- in
- Radius offset from inside conduit
- in
- Developed arc length
- in
- Angle per segment
- deg
- Mark spacing along conduit
- in
- Straight chord between marks
- in
Calculation details
- Calculation basis
- Selection boundary
Recent results
Formulas
- Radius offset = (conduit number from inside - 1) x conduit spacing
- Target centerline radius = inside centerline radius + radius offset
- Developed arc length = target centerline radius x total bend angle in radians
- Angle per segment = total bend angle / segment count
- Mark spacing = developed arc length / segment count
- Chord spacing = 2 x target radius x sin(angle per segment / 2)
Use this calculator
Estimate centerline radius, developed arc length, and segment spacing for a concentric conduit bend.
Read the result
Review the calculated values with their displayed units and assumptions. The result is a planning aid for the stated inputs, not a final equipment or installation decision.
Check before final work
This is a concentric bend layout estimate. It does not verify conduit fill, code compliance, bender shoe geometry, springback, or job-site clearance.
FAQs
What does conduit number from inside mean?
Use 1 for the inside conduit. Each higher number adds one entered spacing amount to the bend radius.
Is mark spacing the same as chord spacing?
No. Mark spacing follows the developed arc length along the conduit. Chord spacing is the straight-line distance between adjacent segment points.
Does this approve the bend for an installation?
No. It is a layout estimate. Verify bender markings, bend sequence, conduit type, springback, and available straight length on the job.