Conduit Offset Bends: Multipliers, Shrink and Marks Explained

An offset steps a run of conduit over to one side so it can clear something in the way, or line up with a box that isn’t square to the run. It’s two equal bends made in opposite directions. Get the math right and the fitting slides onto the knockout with everything sitting flat. Get it a little wrong and you’re back at the truck cutting another length. So it pays to understand what’s happening rather than copying marks off a sticker.

Every offset comes down to two questions. How far apart do the two bends go, and how much does the pipe pull back along the run once you’ve bent it? Both answers fall out of the angle you pick and how deep the offset needs to be.

The multiplier gives you the distance between bends

Choose an angle, multiply the depth of the offset by a fixed number, and that’s the gap between your two marks.

Bend angle	Multiplier	Shrink per inch of depth
10°	6.0	1/16”
22.5°	2.6	3/16”
30°	2.0	1/4”
45°	1.4	3/8”
60°	1.2	1/2”

Thirty degrees is what most electricians reach for without thinking. The multiplier is a clean 2, which is easy to do in your head halfway up a ladder, and the bend is shallow enough that wire pulls through without a fight. The steeper you go, the more length you save when space is tight, and the harder that pull gets. Go shallower, to 10 or 22.5, and a bank of parallel runs looks far tidier because the step is spread over a longer stretch of pipe.

If you want to know where those numbers come from rather than just trusting them, the multiplier is the cosecant of the angle. The pipe between your two bends is the hypotenuse of a triangle whose height is your offset depth. At 30 degrees the cosecant is exactly 2, at 45 it’s 1.414, at 22.5 it’s 2.613. The trade rounds them off. That is the whole trick, and knowing it means you can work out an angle nobody put on a chart.

Where shrink comes from

Shrink catches people because it feels like the pipe is getting shorter, and in a sense it is. Along the line of the run, the diagonal section between your bends does not cover as much ground as the same length of straight pipe would. Travel five inches sideways and you give up some forward travel to do it. That lost forward travel is your shrink, and it always pulls the far end of the conduit back toward you.

Which means you compensate before you bend, not after. Measure to where the fitting has to land, add the shrink, and mark there.

A worked example

A box sits 5 inches off the line of your run, and you’re bending at 30 degrees.

The distance between marks is 5 times 2, so 10 inches. Nothing to it.

The shrink is 5 times a quarter inch, so an inch and a quarter. If the knockout is 48 inches from the end of your existing pipe, you don’t put your first mark at 48. You put it at 49 and a quarter, and the offset swallows that extra length so the fitting ends up exactly where you wanted it.

That single step is the whole difference between an offset that drops in and one that comes up short and gets tossed in the offcut bin. For the depths you hit most often at 30 degrees, the numbers work out like this:

Offset depth	Marks apart	Shrink to add
2”	4”	1/2”
3”	6”	3/4”
4”	8”	1”
5”	10”	1-1/4”
6”	12”	1-1/2”
8”	16”	2”

Shrink is not take-up

Worth being blunt about this one, because it wastes more pipe than any other misunderstanding on the list.

Take-up is a number stamped on your bender, and it belongs to a single 90 degree stub. It tells you how far back from your mark to set the bender so the finished stub height comes out right. It is a property of the tool.

Shrink belongs to the offset, and it exists because of geometry, not because of your bender. Different tool, same shrink.

An offset layout uses the multiplier and the shrink. It does not use take-up at all. If you find yourself subtracting a take-up figure while laying out an offset, stop.

Making the two bends

Measure to the obstruction, add the shrink, and lay down your first mark. From there, measure the distance between bends and make the second. Set the bender’s arrow on the first mark and bend to your angle. Then roll the pipe a half turn so the next bend goes the opposite way, line up the second mark, and bend to the same angle again.

Keep both bends in the same plane. A slight twist between them is what leaves you with a dog-leg that rocks instead of lying flat against the wall, and there’s no fixing that after the fact. The usual cause is letting the conduit rotate slightly in the bender between the two bends, so it’s worth marking a reference line down the length of the pipe with your pencil and keeping that line pointing straight up for both.

Kicks, saddles and rolling offsets

An offset is the base case. Once you have it, the rest of the family follows from the same idea.

A kick is half an offset. One bend rather than two, used when you only need to nudge the pipe over as it leaves a box. Same multiplier logic, only you are not coming back parallel.

A three-point saddle steps over an obstruction and returns to the original line: a centre bend at double your outer angle, with two outer bends bringing it back. The common version is a 45 in the middle and 22.5 at each side. A four-point saddle is just two offsets back to back, which is what you use for a bigger obstruction where you want a flat section on top.

A rolling offset is an offset that moves in two directions at once, both sideways and up. You work out the true offset with Pythagoras from the horizontal and vertical distances first, then treat that result as an ordinary offset depth. The maths is the same once you have the diagonal.

Metric works the same way

None of this is imperial-only. The multipliers are ratios, so they hold whatever unit you measure in. A 120 mm offset at 30 degrees needs marks 240 mm apart. Shrink converts the same way: a quarter inch per inch is a quarter of your depth, so a 120 mm offset at 30 degrees shrinks 30 mm. If you work in millimetres the numbers are arguably easier, because there are no sixteenths to juggle.

The mistakes that cost pipe

Forgetting shrink is the big one, and it always shows up as a fitting that lands short.

Bending the second one the same way as the first gives you a long, lazy Z that goes nowhere near the box. Roll the pipe.

Measuring to the wrong end of the mark matters more than people expect on tight work, so pick a convention, arrow to the mark, and stick to it all day.

And using 45s everywhere because the multiplier is on the chart makes for hard pulls and untidy racks. Save them for when you genuinely lack the length.

Where it gets fiddly

One offset is simple arithmetic. A day’s work is a dozen of them back to back, mixed in with saddles, stub-ups and kicks, each with its own multiplier and shrink, and a single slipped figure costs you a stick of pipe. That’s the case for keeping the numbers off your mental scratchpad. BendPro takes the depth and angle and hands back the marks, the shrink and a labelled diagram, with the bender deductions for Klein, Greenlee, Ideal and Gardner Bender already in it.

But the method above is what it’s doing behind the glass, and it’s worth carrying in your head either way. Benders get left in the van. Geometry doesn’t.