Conduit bending is the trade skill that separates the apprentice from the journeyman in three lessons: take-up, offset, and saddle. The math behind each is small — what takes time is the muscle memory of where to put the foot and how to read the bender. Here is the math part, so the muscle part starts from a correct mark.
Offset — two bends, opposite directions
An offset steps the conduit around a side obstacle: a junction box flush to a wall and the conduit needs to come out behind a stud, or a row of conduits going from a panel down to a tray.
Two pieces of math: the distance between the bends, and the shrink.
Distance between bends
distance = rise × multiplier
Multipliers (printed on every Klein and Greenlee bender handle):
- 22.5° → 2.6
- 30° → 2.0 (the easy one — twice the rise)
- 45° → 1.4
- 60° → 1.15
A 4-inch offset at 30° = 8 inches between marks. Mark, bend, slide, bend in the opposite direction at the second mark. Done.
Shrink
The conduit gets shorter overall by a small amount per inch of rise — because the run is not a straight line anymore.
- 22.5° → 3⁄16" per inch of rise
- 30° → 1⁄4" per inch of rise
- 45° → 3⁄8" per inch of rise
- 60° → 1⁄2" per inch of rise
A 4-inch offset at 30° loses 1 inch overall. If the box is 96 inches from the start of the run, mark the first bend at 97 inches — bending shortens it back to 96.
3-bend saddle — going over an obstacle
A saddle lifts the run over an obstacle in the middle — most commonly another conduit crossing perpendicular. Three bends: a center bend at twice the side angle, two side bends at the half angle.
Common pairings:
- 22.5° / 45° / 22.5° saddle — gentle, used on long runs
- 30° / 60° / 30° saddle — tight, used near panels
Layout for a 30° / 60° saddle:
- Mark the center of the obstacle on the conduit
- Bend a 60° at that mark
- Measure rise × 2.0 from the center mark in each direction (use the 30° multiplier even though center is 60°)
- Bend 30° at each side mark, opposite the center bend
The conduit bending calculator handles both layouts and prints the marks.
Take-up vs deduct
"Take-up" is the distance from the back of the bend to where the conduit was straight, on a 90°. "Deduct" is the same idea from a different reference point. Both are bender-specific — check the chart on your bender:
- ½" EMT, hand bender → 5" deduct
- ¾" EMT, hand bender → 6" deduct
- 1" EMT, hand bender → 8" deduct
- 1¼" EMT, mechanical → 11" deduct
For a stub-up (a 90° from a known horizontal length), measure the desired stub height, subtract the deduct, mark the bend there. The calculator does not handle 90° stubs — they are a different formula.
Common bending mistakes
Forgetting which side of the mark. The bender hooks to one side of the mark depending on offset direction. Mismark by 1⁄8" and the second bend lands wrong. Pencil an arrow on the conduit before bending.
Bending one offset on each end of a run before verifying. Always dry-fit the first bend, confirm direction and rise, then make the second. Stripped, cut-to-length conduit with two wrong offsets goes in the scrap pile.
Overbending past 30°. Each degree past 30 adds resistance to the wire pull. Three 90° elbows + a 30° offset hits the NEC 358.26 / 344.26 cap of 360° between pull points — add a junction box or pull box before that.
Mixing degree references. Some chart conventions print the side-bend angle (30° saddle = 30° sides + 60° center); some print the center. Read the footnotes on your bender chart.
Estimate only. The conduit bending calculator uses the standard multipliers and shrink table for offsets and 3-bend saddles. Verify against your specific bender's printed deduct and shoe-radius chart, and confirm your final layout meets NEC 358.26 / 344.26 bend-count limits between pull points.