Conduit Bending Calculator
Offset, 3-bend saddle, and 90-degree stub-up math. Distance between bends, shrink, and back-of-bend marks. Free, no account required.
Bend Type
How far the run must shift to clear the obstacle.
12" between marks
Measure between the two bend marks.
How the math works
- Offset: distance between bends = offset depth × the multiplier for the chosen angle. The exact value is offset / sin(angle).
- Shrink: the offset pulls the end of the conduit back. Deduct the shrink from your end measurement before marking.
- 3-bend saddle: 45° center bend with 22.5° outer bends. Outer marks sit 2.5× the obstacle height from center.
- 90° stub: back-of-bend mark = stub height − take-up. Take-up depends on conduit size and bender.
Check your bender
Take-up and multiplier values vary slightly by bender brand and conduit type. Always confirm against the markings stamped on your bender before cutting an expensive run.
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Conduit bending values use standard trade multipliers and EMT take-up figures. Confirm against your specific bender and conduit. Not a substitute for manufacturer instructions.
How the conduit bending calculation works
Conduit bending math is trigonometry with the trig already done for you. Every offset is a right triangle: the offset height is the opposite side, the distance between bends is the hypotenuse, and the multiplier is simply the cosecant of the bend angle. That is why the standard multipliers are what they are. Cosecant 30 is 2.0, cosecant 45 is 1.414, cosecant 22.5 is 2.6, and cosecant 60 is 1.155.
Shrink is the second half of the calculation and the half that gets forgotten on the job. Bending an offset pulls the end of the conduit back toward you, so the run comes up short unless you add the shrink amount before you cut. Shrink per inch of offset is also fixed per angle: 3/16 inch for 10 degrees, 1/4 inch for 22.5, 3/8 inch for 30, and 1/2 inch for 45.
A three-bend saddle over an obstruction uses a center bend of 45 degrees with two 22.5 degree side bends, and the distance from the center mark to each side mark is 2.5 times the obstruction height. A 90 degree stub-up uses take-up, which is a property of the bender shoe rather than of trigonometry: commonly 5 inches for 1/2 inch EMT, 6 inches for 3/4 inch, 8 inches for 1 inch, and 11 inches for 1 1/4 inch.
Step by step
- 1
Pick the bend angle
30 degrees is the general-purpose offset. Shallower angles pull easier and take more length, steeper angles fit tighter spaces.
- 2
Multiply for spacing
Distance between bends = offset height x the multiplier for that angle.
- 3
Add the shrink
Shrink = offset height x shrink-per-inch for that angle. Add it to your measurement before cutting or marking.
- 4
Mark the conduit
Measure from the end to the first mark, then the calculated distance to the second.
- 5
For a 90, subtract take-up
Mark = desired stub height minus the bender take-up for that trade size.
- 6
Respect the bend limits
358.24 for EMT and 344.24 for RMC require the radius of the curve not be less than Chapter 9 Table 2, and 358.26 limits a run to 360 degrees total between pull points.
Worked example
Make a 6 inch offset in 3/4 inch EMT using 30 degree bends. Where do the marks go and how much length is lost?
- Multiplier for 30 degrees = 2.0.
- Distance between bends = 6 x 2.0 = 12 inches.
- Shrink per inch at 30 degrees = 3/8 inch.
- Total shrink = 6 x 0.375 = 2.25 inches.
Answer: Marks 12 inches apart, and add 2 1/4 inches to the overall measurement to compensate for shrink. Skipping the shrink allowance leaves the run 2 1/4 inches short at the box.
How this is tested on the exam
Bending math shows up more often on practical and hands-on portions than on written exams, but written exams do test the multipliers and the 360 degree limit in 358.26. If you are studying for a state that includes a practical component, the multipliers and shrink values are worth committing to memory rather than deriving.
Frequently asked questions
Where do the offset multipliers come from?
Each multiplier is the cosecant of the bend angle. Cosecant 10 is 6.0, cosecant 22.5 is 2.6, cosecant 30 is 2.0, cosecant 45 is 1.414, cosecant 60 is 1.155. The offset is the opposite side of a right triangle and the distance between bends is the hypotenuse.
What is shrink and why does it matter?
Bending an offset shortens the effective straight-line length of the conduit, because part of the run is now traveling diagonally. If you do not add the shrink amount to your measurement before marking, the finished piece lands short of the box.
What is take-up on a 90 degree bend?
Take-up is the distance from the end of the conduit to the bender's arrow mark needed to produce a stub of a given height. It is a property of the bender shoe radius, not of trigonometry. Typical EMT values are 5 inches for 1/2 inch, 6 inches for 3/4 inch, 8 inches for 1 inch, and 11 inches for 1 1/4 inch.
How many bends are allowed between pull points?
358.26 limits EMT to not more than the equivalent of four quarter bends, 360 degrees total, between pull points. Article 344.26 sets the same limit for rigid metal conduit. Minimum bend radius comes from Chapter 9 Table 2.