Bending Reference
Conduit Shrink Calculator
The shrinkage chart for every standard bend angle, applied to offsets, kicks, and saddles. Shrink depends on the angle and the height, not the conduit size, so one chart covers 1/2 inch through 1-1/4 inch EMT. Interactive calculator, worked examples, and the formula.
Conduit Shrinkage Chart
Shrink per inch of offset or kick height by bend angle. The multiplier column is the mark spacing factor for the same offset, the bender-chart constant where one is printed and the exact 1 / sin where not (15°), included so you can lay out the whole offset from one table.
| Bend Angle | Bender chart | Sharp-corner geometry | Difference | We use | Multiplier |
|---|---|---|---|---|---|
| 10° | 1/16" | 0.087 | +40.0% | chart | 6.0 |
| 15° | not published | 0.132 | no chart value | geometry | 3.86 |
| 22.5° | 3/16" | 0.199 | +6.1% | chart | 2.6 |
| 30° | 1/4" | 0.268 | +7.2% | chart | 2.0 |
| 45° | 3/8" | 0.414 | +10.5% | chart | 1.4 |
| 60° | 1/2" | 0.577 | +15.5% | chart | 1.2 |
Why two columns. Bender manufacturers print a short table of convenient fractions, and that is what the calculator applies wherever a published value exists, so our marks agree with the chart on your bender. The geometry column is what the bend angle alone gives, modelled as a sharp corner. They are not the same number, and the difference column says by how much. Where a manufacturer publishes nothing there is no chart value to use, so the calculator falls back to the geometry. That is how the 15 degree row is answered at all, and it is why an angle can be added to this tool without anyone having to invent a fraction for it.
Derived from the bend angle alone, as a sharp corner with no bend radius. A real bender lays an arc and shrinks less than that, by under 1 percent at 10 degrees and by roughly a third at 60, so treat this as the conservative figure and check your first bend.
Total Shrink by Offset or Kick Height
Pre-computed total shrink (height × the constant above) for the three most common field angles. Read down to your offset height or kick rise and subtract the value from your first mark.
| Height | Shrink @ 22.5° | Shrink @ 30° | Shrink @ 45° |
|---|---|---|---|
| 2" | 3/8" | 1/2" | 3/4" |
| 3" | 9/16" | 3/4" | 1-1/8" |
| 4" | 3/4" | 1" | 1-1/2" |
| 5" | 15/16" | 1-1/4" | 1-7/8" |
| 6" | 1-1/8" | 1-1/2" | 2-1/4" |
| 8" | 1-1/2" | 2" | 3" |
| 10" | 1-7/8" | 2-1/2" | 3-3/4" |
Calculate Shrink for Your Bend
Enter your offset height and angle to get exact shrink, travel, and marks with a diagram. Switch the bend type to kick-90 to get shrink per inch of kick, or to a saddle for the three- and four-point shrink.
Shrink by Bend Type
Offset shrink
An offset is two equal bends. Total shrink is the offset height times the shrink-per-inch constant for the angle. A 4 inch offset at 30 degrees shrinks 4 × 1/4" = 1". Subtract that from the distance to your first mark so the far leg lands where the straight run is supposed to resume.
Kick shrink
A kick is one bend that pushes the pipe off its straight line. Shrink per inch of kick height is identical to the offset constant, because the geometry of the single bend is the same. Kick a run 3 inches at 30 degrees and the pipe reaches 3 × 1/4" = 3/4" shorter, so allow for 3/4" on the leg past the kick when you measure. The dedicated kick 90 calculator places both the 90 and the kick mark together.
Saddle shrink
A three-point saddle is a center bend with two outer bends at half that angle, so its shrink is keyed to the outer angle and the saddle depth. A four-point saddle is two opposing offsets, so its shrink is roughly double a single offset of the same depth. The saddle bend calculator works out the exact spacing and shrink for both.
Does Conduit Size Change the Shrink?
No. This is the single most common shrink question, and the answer is that shrink is a function of the bend angle and the height of the offset or kick, not the diameter of the pipe. A 30 degree offset shrinks 1/4 inch per inch of height on 1/2 inch EMT, on 3/4 inch EMT, and on 1 inch EMT alike. There is no separate "3/4 EMT shrinkage" number.
What does change with conduit size is the take-up (deduct) on a 90 degree stub: 5 inches for 1/2", 6 inches for 3/4", 8 inches for 1", all published by Klein and Gardner Bender, plus 11 inches for 1-1/4", which is a field value no manufacturer document we hold confirms. That is a different measurement from shrink, and it is easy to mix the two up because both shorten the pipe. Use the 90 degree deduction chart for take-up by size, and this page for offset and kick shrink by angle.
Worked Example: 6-Inch Offset at 30 Degrees
Given: A beam forces the run up 6 inches. The point where the offset must finish is 48 inches from the end of your conduit. You bend at 30 degrees for easy math.
Step 1: Shrink. Shrink = 6 × 1/4" = 1-1/2 inch. The run will be 1-1/2 inch shorter after both bends.
Step 2: First mark. 48 − 1-1/2 = 46-1/2 inches to the first bend mark, so the far leg still lands at 48 inches after the pipe pulls in.
Step 3: Second mark. Travel = 6 × 2.00 (the 30 degree multiplier) = 12 inches. Second mark at 46-1/2 + 12 = 58-1/2 inches.
Result: Bend 30 degrees at each mark in the same plane. The 6 inch rise clears the beam and the run resumes exactly at 48 inches because you took out the shrink.
Frequently Asked Questions
How much does conduit shrink per inch of offset?
Shrink per inch of offset height is 1/16 inch at 10 degrees, 3/16 inch at 22.5 degrees, 1/4 inch at 30 degrees, 3/8 inch at 45 degrees, and 1/2 inch at 60 degrees. Multiply that constant by the offset height to get total shrink. A 4 inch offset at 30 degrees shrinks 4 x 1/4 = 1 inch.
How much shrink per inch of kick?
A kick is a single bend, so shrink per inch of kick height uses the same constants as an offset: 1/4 inch of shrink per inch of kick at 30 degrees, 3/16 inch at 22.5 degrees, and 3/8 inch at 45 degrees. If you kick a run 3 inches at 30 degrees, the conduit reaches 3 x 1/4 = 3/4 inch shorter, so allow for 3/4 inch on the leg past the kick.
Does conduit shrink depend on the pipe size?
Not in the published charts. The bender-chart shrink constant is set by the bend angle alone: a 30 degree offset is charted at 1/4 inch per inch of height whether you are bending 1/2 inch, 3/4 inch, or 1 inch EMT, which is why one shrink chart covers every size. What clearly changes with conduit size is take-up on a 90 degree bend (the deduct), not the charted shrink constant.
What is the shrink for 3/4 EMT?
The same as any other size. No manufacturer publishes a separate 3/4 inch EMT shrink value: at 30 degrees it is charted at 1/4 inch per inch of offset height and at 45 degrees 3/8 inch per inch, for every diameter. If you were looking for the 90 degree deduction for 3/4 inch EMT, that is 6 inches of take-up, which is a different number and does vary by size.
Why does bending conduit make the run shorter?
When you put a bend in conduit, the pipe follows the hypotenuse of a triangle instead of running straight and then square, so the two ends pull closer together. That lost distance is shrink. The steeper the angle, the more the pipe rises over a shorter travel, so the more it shrinks per inch of height. You compensate by subtracting the shrink from the distance to your first bend mark.
How do I use shrink to place my first bend mark?
Measure from a fixed reference (a box, a wall, the end of the pipe) to where the obstruction or the far side of the offset needs to land, then subtract the total shrink. Example: the offset needs to clear a pipe 40 inches away, and you are bending a 5 inch offset at 30 degrees. Shrink = 5 x 1/4 = 1-1/4 inch, so your first mark goes at 40 - 1-1/4 = 38-3/4 inches.
Where does the shrink constant come from?
From the published field chart, not from a formula. The chart gives 1/4 inch of shrink per inch of offset height at 30 degrees and 3/8 inch at 45 degrees, and those charted values are what this calculator uses. They are close to tan(angle / 2), the geometry of a sharp corner, but they are not equal to it and they are not a rounding of it: the chart runs about 6 percent below that curve at 22.5 degrees and about 29 percent below at 10 degrees, and tan(22.5 degrees) = 0.414 is nearer 7/16 than the charted 3/8. Use the chart, because that is what the trade lays out to. The multiplier comes from the same chart and is applied the same way: 6.0, 2.6, 2.0, 1.4 and 1.2 are 1 / sin(angle) rounded for a tape measure, which is why the multiplier is the same on every conduit size. For an angle the chart does not list, this calculator falls back to tan(angle / 2) for shrink and to the exact 1 / sin(angle) for the multiplier.
More Bending References
Printable Cheat Sheet
Every bending constant on one page. Print, save the PDF, or download the image for your phone.
Conduit Bending Calculator
Every bend family the calculator carries as an interactive 3D rendering or flat diagram, with verified bender profiles.
Offset Multiplier Chart
Multipliers and travel for 10 to 60 degree offsets, with worked examples.
Kick 90 Calculator
Kick marks, travel, and shrink per inch of kick for stub-and-kick combos.
90° Deduction Chart
Take-up, deduct, radius, and gain for 1/2" through 1-1/4" EMT by size.
Saddle Bend Calculator
3-point and 4-point saddle marks, spacing multipliers, and shrink.