Conduit mark spacing worksheet
Offset Bend Spacing Calculator
Calculate the distance between offset bend marks and locate the second mark from a known first mark.
Calculate Offset Bend Spacing
Enter offset height, bend angle, and first mark distance to calculate bend spacing and the second mark.
Result
Bend spacing
8.00 in
Second mark
26 in
Measured from the same reference end as the first mark.
Result notes
Keep the entered values, assumptions, and result together when adding this calculation to job notes or submittal records. Final installation choices should align with the applicable code edition, equipment listing, manufacturer instructions, local amendments, and AHJ requirements.
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Related tools
Formula and field context
Calculate the distance between offset bend marks and locate the second mark from a known first mark.
Formula context
Offset Bend Multiplier Chart
For a two-bend conduit offset, distance between bends equals offset height times the selected multiplier: 10 deg = 6.0, 22.5 deg = 2.6, 30 deg = 2.0, 45 deg = 1.414, and 60 deg = 1.155. A 4 inch offset at 30 deg uses the 2.0 multiplier, so the marks are 8 inches apart before shrink and bender-reference checks. Use this chart for common offset multiplier questions without creating angle-specific pages.
Formula
Distance between bends = offset height x multiplier. Shrink allowance = offset height x shrink per inch.Variables to keep with the result
- Offset height is the rise or drop needed to clear an obstruction or change elevation.
- Bend angle is the equal angle used for both bends in the offset.
- Multiplier converts offset height into mark spacing along the conduit.
- Shrink allowance estimates how much the finished run shortens through the offset geometry.
Formula and variables
Offset bend spacing is the distance between the two bend marks for a simple offset. The formula is spacing = offset height x multiplier, where multiplier = 1 / sin(angle). If the first mark is already measured from one end of the conduit, the second mark is second mark = first mark + spacing. Both marks must be measured from the same reference end.
Field example
Suppose the first mark is 18 in from the end of the conduit and the offset must rise 4 in using 30 degree bends. The 30 degree multiplier is 2.0, so spacing = 4 x 2.0 = 8 in. The second mark is 18 in + 8 in = 26 in from the same end. If the angle changes to 22.5 degrees, the spacing increases because the multiplier is larger.
Assumptions and layout limits
This worksheet is for a two-bend offset in one plane with equal bend angles. It does not include box offsets, kicks, rolling offsets, saddles, couplings between marks, or take-up rules for a specific bender. When the run includes a fixed box, coupling, or obstruction edge, confirm whether the first mark should be adjusted for take-up or shrink before laying out the second mark.
Common mistakes
Common mistakes include measuring the second mark from the first mark instead of from the same conduit end, using the obstruction distance as bend spacing, forgetting to change the multiplier when the bend angle changes, and flipping the conduit between bends. Mark the reference end clearly and keep both bends in the same plane.