What is the offset multiplier and where does it come from?

The offset multiplier is one divided by the sine of the bend angle. It converts the height you need to clear an obstruction into the distance between the two bend marks. A 30-degree bend uses a multiplier of 2, a 45-degree bend about 1.4, and a 60-degree bend about 1.15.

What is shrink and why does it matter?

Bending raises the conduit, which shortens the run between fixed points. Shrink per inch of offset is the cosecant relationship and equals roughly 0.25 inch per inch at 30 degrees, 0.375 at 45, and 0.5 at 60. The tool totals shrink so you can shift your first mark to keep the run on target.

How is the take-up used for a stub-up?

Take-up is the distance the bend itself consumes, specific to conduit size and bender. For half-inch EMT it is about 5 inches. The mark-to-bend equals the desired stub height minus the take-up, placed from the free end with the arrow on the bender pointing at the mark.

How does a three-point saddle work?

A saddle clears a round obstruction with a 45-degree center bend flanked by two 22.5-degree bends. The center mark sits at the obstruction. The side marks are placed at 2.5 times the obstruction height on each side of center, and the run shrinks about 0.1875 inch per inch of saddle.

What about back-to-back bends?

A back-to-back bend makes a U with two stubs facing the same way. Bend the first stub, then measure the full back-to-back length to the second mark and bend with the bender reversed so both 90s share the same plane and height.

Electrical Conduit Bending Calculator

Bending conduit accurately comes down to a few trigonometric relationships built into every hand bender. This calculator gives you the gain, take-up, and mark-to-bend dimensions for the everyday bends — stub-ups, offsets, saddles, and back-to-back — so you can lay out a run without re-deriving the math on the deck.

How it works

The key relationships, where the offset angle drives the geometry:

offset multiplier = 1 / sin(angle)
distance between bends = offset height × multiplier
shrink per inch  = (1 / sin(angle)) − (1 / tan(angle))   (cosecant − cotangent)
total shrink = offset height × shrink-per-inch
stub mark-to-bend = stub height − take-up
saddle side marks = center ± 2.5 × obstruction (45° center bend)

Take-up is the length the 90-degree bend consumes and is fixed per conduit size and bender shoe: roughly 5 in for 1/2 in EMT, 6 in for 3/4 in, 8 in for 1 in. Subtracting it from the desired stub height tells you where to set the arrow.

Example and tips

To clear a 6 in obstruction with a 30-degree offset, the marks sit 12 in apart (6 × 2), and the run shrinks about 1.5 in (6 × 0.25), so shift your first mark 1.5 in toward the bender. For a 10 in stub in 1/2 in EMT, mark 5 in from the end (10 − 5 take-up). Always bend test pieces first and keep the bender foot pressure even so the take-up matches the rated value.