Conduit Bending Multipliers & Offset Shrink Chart

Bending · The math · Updated 2026-08-07

An offset multiplier turns an offset depth into the distance between your two bend marks: distance between marks = offset depth × multiplier. The shrink constant tells you how much shorter the run gets once the pipe travels a diagonal, so you add it back before the first mark and the conduit still lands where you measured.

Here is the full chart for 10, 22.5, 30, 45, and 60 degree bends, the trigonometry behind the numbers, worked examples with the arithmetic shown, and the mistakes that cause dog-legs and short sticks. Tape the chart inside your hard hat; read the rest once so you know when the rounded constants bite.

The offset multiplier and shrink chart

Pick an angle, multiply the offset depth by the multiplier for the distance between marks, then by the shrink constant for how much the run shortens. The two always travel together: use the multiplier without the shrink and the offset clears the obstruction, but the stick comes up short of the box.

How to lay out an offset with the chart

1. Measure the offset depth: Depth is the elevation change the pipe has to make, measured center to center - from the plane the conduit runs on now to the plane it lands on. Measure to pipe center, not edge, or the offset sits proud by half a diameter.
2. Measure the distance to the obstruction: Hook your tape on the free end of the conduit and measure to where the offset must begin - the near edge of the beam or duct you are clearing.
3. Compute shrink and place the first mark: Multiply depth by the shrink constant, then add the result to the distance you just measured. At 30 degrees with a 5 inch depth, shrink is 5 × 1/4" = 1-1/4", so a 42" measurement becomes a first mark at 43-1/4".
4. Multiply for the second mark: Distance between marks = depth × multiplier. Here that is 5" × 2.0 = 10", so the second mark goes at 53-1/4".
5. Bend, flip, bend: Bend the first mark to the chosen angle, slide the bender to the second mark, rotate the conduit 180 degrees, and bend to the same angle with both bends in one plane. The step-by-step EMT bending guide covers bender orientation, air bending, and checking the finished offset.

Worked examples with the arithmetic shown

Every row uses only the chart values - check the math once by hand and after that you will trust the pattern. Decimals are converted to the nearest sixteenth, which is as fine as a tape mark gets.

Now put the 4 inch, 22.5 degree offset on a real wall: the conduit must jump a beam whose near edge is 38 inches away. Shrink is 4 × 3/16" = 12/16" = 3/4", so the first mark goes at 38 + 3/4 = 38-3/4". The distance between marks is 4 × 2.6 = 10.4", which is 10-3/8" on a tape, so the second mark lands at 38-3/4" + 10-3/8" = 49-1/8". Bend both marks to 22.5 degrees and the offset starts right at the beam with the run length preserved.

Where the multipliers come from

The multiplier is the cosecant of the bend angle: 1 ÷ sin(angle). An offset is a right triangle: the depth sits opposite the bend angle and the conduit between the bends is the hypotenuse, so its length is depth ÷ sin(angle). At 30 degrees, sin = 0.5 exactly, which is why the multiplier is exactly 2.0. At 45 degrees, 1 ÷ 0.7071 = 1.414, rounded to 1.4. At 60 degrees, 1 ÷ 0.8660 = 1.155, rounded to 1.2. At 22.5 degrees, 1 ÷ 0.3827 = 2.613, rounded to 2.6. At 10 degrees, 1 ÷ 0.1736 = 5.76, which the trade rounds all the way up to 6.0 - the loosest rounding on the chart.

Shrink has its own identity: the true value per inch of depth is the tangent of half the bend angle. At 30 degrees that is tan 15° = 0.268, which the field rounds to 1/4" (0.25). At 45 degrees, tan 22.5° = 0.414 against the chart's 3/8" (0.375). At 60 degrees, tan 30° = 0.577 against 1/2" (0.5). At 10 degrees, the true 0.0875 gets rounded to 1/16" (0.0625). The rounding always understates shrink slightly. On one shallow 30 degree offset the error is under an eighth of an inch - invisible. Across four stacked offsets on a rack it becomes a visible gap at the last coupling, which is why layout-critical work deserves exact trig.

Why 30 degrees is the default

Three reasons. The multiplier is exactly 2, so layout math is doubling in your head instead of multiplying by 2.6 on a ladder. The shrink is a clean 1/4 inch per inch of depth, so fractions stay friendly. And 30 degrees balances pull friction against fit: shallow 10 degree bends pull easily but need a long runway to develop depth, while 45 and 60 fit tight quarters at the cost of harder pulls and more shrink. When nothing forces your hand, bend 30.

Rolling offsets: square the rise and the roll

When the pipe has to move up and over at the same time, you have a rolling offset. Treat the rise and roll as legs of a right triangle: true depth = √(rise² + roll²). A 3 inch rise with a 4 inch roll is the classic 3-4-5 triangle: √(9 + 16) = √25 = 5 inches of true depth. From there it is an ordinary offset - at 30 degrees the marks go 5 × 2.0 = 10 inches apart with 5 × 1/4" = 1-1/4" of shrink. The extra step is rotation: the bender has to be rolled off plumb so the offset plane points along the diagonal - the part most people eyeball, and where most dog-legs come from.

Multiplier, shrink, take-up, gain: keep them straight

Four numbers get blended together in field talk, and mixing them up ruins conduit. The multiplier spaces the two marks of an offset. Shrink is how much shorter the overall run gets because the pipe now travels a diagonal. Take-up, also called the deduct, belongs to stub 90s only: it is the amount you subtract from the stub height before marking, because the bender's radius consumes part of the rise. Gain is the opposite bookkeeping for 90s - the length you save because the pipe corners on an arc instead of a square corner. Offsets use multiplier and shrink; 90s use take-up and gain. Never cross them.

A 12 inch stub in 1/2 inch EMT: take-up is 5 inches, so 12 - 5 = 7. Mark 7 inches from the end, line it up with the bender arrow, and the stub finishes 12 inches to the back of the bend.

Common mistakes

• Applying shrink after marking. Shrink moves the first mark farther out; add it to the tape measurement before you mark. After the bend it is too late.
• Using take-up on an offset. The 5 inch deduct belongs to stub 90s on a 1/2 inch bender. Offsets use only the multiplier and shrink chart.
• Measuring depth to the edge of the obstruction. Offsets are center of pipe to center of pipe. Add clearance deliberately - do not let it appear or vanish by accident.
• Dog-legging the second bend. Both bends must sit in one plane. Sight down the pipe and keep the conduit seated in the bender hook so it cannot rotate.
• Grabbing 60 degrees out of habit. Steeper offsets pull harder and shrink more. Use the shallowest angle the space allows.
• Ignoring springback. An air bend relaxes a degree or two when you release pressure. Bend slightly past the target and verify with a level or protractor before moving on.
• Blowing the bend budget. Every offset adds two bends' worth of degrees to the run. Count them against the 360 degree limit before you commit - details below.

Marks computed with exact trig, shrink included. Conduit Fill & Bending Calc by Panda Taps runs the true cosecant and shrink math for offsets, rolling offsets, saddles, kicks, and 90s, then rounds only the final tape marks to a sixteenth. It also handles conduit fill, box fill, voltage drop, and ampacity with derating, works offline in the field, and needs no account. On the App Store for iPhone and iPad. Download Conduit Fill & Bending Calc on the App Store.

Frequently asked questions

What is the multiplier for a 30 degree offset?

The 30 degree offset multiplier is 2.0, so the distance between bend marks is twice the offset depth. Shrink is 1/4 inch for every inch of depth. A 4 inch offset needs marks 8 inches apart and shortens the run by 1 inch.

How do you calculate conduit shrink?

Multiply the offset depth by the shrink constant for your angle: 1/16 inch per inch of depth at 10 degrees, 3/16 at 22.5, 1/4 at 30, 3/8 at 45, and 1/2 at 60. Add the result to your measured distance before placing the first bend mark.

Why is the 45 degree offset multiplier 1.4?

The multiplier is the cosecant of the bend angle, meaning 1 divided by its sine. The sine of 45 degrees is about 0.707, and 1 divided by 0.707 is 1.414, which the trade rounds to 1.4.

What is the difference between shrink and take-up?

Shrink is how much shorter a run gets after an offset, and you add it before the first mark. Take-up, or deduct, applies only to stub 90s: you subtract it from the stub height before marking, for example 5 inches with a 1/2 inch EMT bender.

Keep reading

• How to Bend EMT Conduit: 90s, Offsets & Saddles
• Conduit Fill Chart: How Many Wires Fit in EMT?
• Voltage Drop: the Formula, the 3% Rule, and Worked Examples