Conduit Bending Calculator
Calculate precise bending marks for two-bend offsets, three-point saddles, and 90° stubs. Instantly determine multipliers, shrinkage deductions, and track your total bend degrees against NEC code limits.
How to measure and bend conduit accurately
Applying Offset Multipliers
A two-bend offset uses simple right-triangle trigonometry. To calculate the distance between your two bend marks, multiply the height of the obstacle by the cosecant multiplier of your chosen angle. For example, if you are clearing a 4-inch pipe using 30-degree bends (Multiplier = 2.0), your marks will be exactly 8 inches apart on the straight EMT.
Calculating Shrinkage
As the conduit angles upward to clear an obstacle, the overall linear length of the pipe shortens. This is known as "shrink." If you ignore shrinkage, your conduit will end up too short to reach the final junction box. You must calculate the total shrinkage and add it to your starting mark to ensure the pipe clears the obstacle exactly where intended.
Marking a 3-Point Saddle
A 3-point saddle uses three bends to cross over an obstacle: a steep center bend and two shallower outer bends. Because the saddle forms an arc, it shrinks the center point of the pipe back toward you. You must mark the physical center of the obstacle on the pipe, and then push that mark forward by the calculated Center Mark Shrink before laying out the two outer marks.
The 90-Degree Deduct (Take-Up)
When making a 90° stub-up, the conduit curves around the bender shoe, consuming pipe length. You must subtract the bender's "Take-Up" deduct from your desired finished stub height. If you want a 20-inch stub on 3/4" EMT (6-inch deduct), you place your mark at exactly 14 inches and align it with the bender's Arrow mark.
Frequently asked questions
What is the NEC 360-degree rule?
The National Electrical Code (NEC 358.26) strictly limits the total number of bends in a continuous conduit run between two pull points (junction boxes) to the equivalent of four 90-degree bends, or 360 degrees total. This ensures that wire can be physically pulled through the pipe without exceeding tension limits or stripping the insulation off the copper wire.
What does the "Star" mark on the bender mean?
Standard hand benders have multiple reference marks. The Arrow is used for standard stubs and offsets. The Star mark is specifically used for "Back-to-Back" 90-degree bends. It allows you to align the bender so that the outside back edge of the finished bend lands exactly on your mark, rather than calculating the complex outer-radius geometry yourself.
Which notch do I use for the center of a saddle?
When bending the steep center angle of a 3-point saddle (usually 45 degrees), you must align your adjusted center mark with the "Rim Notch" or "Tear Drop" mark on the bender shoe, not the Arrow. Once the center bend is complete, you flip the bender around and use the Arrow mark for the two outer bends.
About this calculator
This Conduit Bending Calculator applies geometric cosecant multipliers and field-standard shrink constants to map precise bend profiles for electrical metallic tubing (EMT).
The mathematical engine utilizes the following field logic:
Offset Spacing:
Distance Between Marks = Rise × Cosecant(Angle)
Total Shrinkage = Rise × Shrink Constant per Inch
3-Point Saddle:
Center-to-Outer Mark Spacing = Depth × Cosecant(Outer Angle)
Center Mark Push (Shrink) = Depth × Center Shrink Constant
90° Stub-Up:
Mark Position = Desired Finished Height − Bender Deduct
(Standard Deducts: 1/2" = 5" | 3/4" = 6" | 1" = 8" | 1-1/4" = 11")
NEC 358.26 Tracker:
Current Capacity = 360° − Σ(All Offset and Saddle Angles)
Distance Between Marks = Rise × Cosecant(Angle)
Total Shrinkage = Rise × Shrink Constant per Inch
3-Point Saddle:
Center-to-Outer Mark Spacing = Depth × Cosecant(Outer Angle)
Center Mark Push (Shrink) = Depth × Center Shrink Constant
90° Stub-Up:
Mark Position = Desired Finished Height − Bender Deduct
(Standard Deducts: 1/2" = 5" | 3/4" = 6" | 1" = 8" | 1-1/4" = 11")
NEC 358.26 Tracker:
Current Capacity = 360° − Σ(All Offset and Saddle Angles)