How the jobs are made
Each job is drawn from invented measurements on a 10 ft stick of 1/2, 3/4 or 1 in EMT: box heights a real wall would have, pipes and ducts of real sizes, saddles no deeper than 6 in, bends never so close that they overlap on the bender shoe, and at least 2 in of straight conduit between a box or cabinet and the nearest bend. Lengths are worked in sixteenths of an inch, and an answer within one rounding step (1/16 or 1/8 in) of the key is marked right. Drawings are not to scale where a depth would be too small to see.
A worked example
In set QRS234 (year 2, field rules, 1/2 in EMT) the ceiling steps down 4 in at a soffit 26 1/2 in from the box. With 30° bends the distance between bends is 4 × 2 = 8 in and the shrink is 4 × 1/4 = 1 in. Mark B goes at 26 1/2 + 1 = 27 1/2 in from the end, and mark A 8 in back, at 19 1/2 in. In exact trig the shrink is 4 × 0.2679 (tan 15°), which rounds to 1 1/16 in. Open set QRS234
Field rules or exact trig
| Bend | Field multiplier | csc | Field shrink per inch | tan(½ bend) |
|---|---|---|---|---|
| 10° | 6 | 5.7588 | 1/16 in | 0.0875 |
| 22.5° | 2.6 | 2.6131 | 3/16 in | 0.1989 |
| 30° | 2 | 2.0000 | 1/4 in | 0.2679 |
| 45° | 1.4 | 1.4142 | 3/8 in | 0.4142 |
| 60° | 1.2 | 1.1547 | 1/2 in | 0.5774 |
Questions
How do you calculate a conduit offset?
Multiply the depth of the offset by the multiplier for your angle to get the distance between bends. Multiply the depth by the shrink per inch to get the shrink. Working toward an obstruction, put the second mark at the distance to the obstruction plus the shrink, and the first mark the distance between bends back toward the end.
What are the offset multipliers and shrink per inch?
As printed on hand benders: 10° times 6 with 1/16 in of shrink per inch of offset, 22.5° times 2.6 with 3/16 in, 30° times 2 with 1/4 in, 45° times 1.4 with 3/8 in, and 60° times 1.2 with 1/2 in.
How do you bend a 3-point saddle?
With a 45° center bend and two 22.5° bends: put the center mark at the distance to the center of the pipe plus 3/16 in for every inch of depth, and the outer marks 2.5 times the depth either side. Bend the center on the rim notch and the outer bends on the arrow.
What is take-up and what is gain?
Take-up (deduct) is what you subtract from a stub height to place the arrow mark: 5, 6 and 8 in for 1/2, 3/4 and 1 in EMT on common hand benders. Gain is how much shorter a 90 is than its two legs measured to the back of the bend; you need it to lay out a second 90 or a cut length. Gain differs from bender to bender, so bend a 90 in a scrap, add its two legs and take away the length of the scrap.
Why do field rules and exact trig give different marks?
The bender table rounds. The true 60° multiplier is the cosecant, 1.1547, not 1.2, and a 3-point saddle uses 2.5 where the cosecant of 22.5° is 2.6131. Pick the mode your class uses: every key here follows it, and the other mode's answer gets a note.
How many degrees of bends are allowed in a run of EMT?
The NEC (358.24 in the 2023 edition, 358.26 in 2020 and earlier) allows no more than 360° of bends between pull points, counting the bends inside offsets, saddles and kicks. A run with more needs a pull box or conduit body in between.
How do you work out a rolling offset?
Measure the rise and the roll, square each, add them and take the square root: that is the true offset. A 3 in rise and 4 in roll gives a 5 in true offset. Then bend an ordinary offset of that depth, rolled so it points at the target.
Sources, read October 25, 2026: Greenlee Site-Rite hand bender use guide 52034125 (2023, PDF); Klein Tools Conduit Bender Guide (2012, PDF); Gardner Bender hand bender instruction manual (PDF) and Hand Benders How To Guide (2020, PDF); Milwaukee conduit bender instructions 58-14-4060d3 (2020, PDF); Wheatland Tube steel EMT submittal sheet (PDF): outside diameters; Bill Bamford, Bending conduit and tubing using hand benders (Mike Holt Enterprises, 2012, PDF); IBEW Local 903 bending book, revision II (PDF): rolling offsets and segment bends; EC&M Code Q&A, NEC requirements for EMT bends (2023). NEC sections are cited by number only, from the 2023 edition (NFPA 70).