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Conduit Bending Calculator

Enter the offset height, saddle or stub-up and get the marks to measure and bend.

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A conduit bending calculator turns an offset height, obstruction size or stub height into the marks you measure from the end of the conduit before it goes into the bender. Pick one of five bends: a two-bend offset, a 3-point saddle, a 4-point saddle, a 90° stub-up or a back-to-back 90°. The result lists every mark in bending order with the bend angle and the bender symbol to line up with, plus the distance between bends, the shrink and the multiplier where they apply. Multipliers and shrink come either from the rounded constants in the Klein Tools bender guide or from exact trigonometry, and stub-ups use a standard hand-bender take-up for EMT or Rigid / IMC unless you type your own. Lengths accept fractions such as 10 1/2 and can be entered in inches, feet, millimetres or centimetres.
Conduit bending calculator example

How to use the Conduit Bending Calculator

  1. Choose the type under “Bend”: “Offset (two bends)”, “3-point saddle”, “4-point saddle”, “90° stub-up” or “Back-to-back 90°”.
  2. For an offset or saddle, type the “Offset or obstruction height” and pick its unit. Then set “Bend angle”, or “Centre bend” for a 3-point saddle.
  3. For an offset, set “You measured” to “From the conduit end to the first bend” or “From the conduit end to the obstruction”, then type the “Distance”. For saddles, the distance runs to the centre (3-point) or the start (4-point) of the obstruction.
  4. For a 4-point saddle, also enter the “Obstruction width”.
  5. For a stub-up or back-to-back, type the “Stub height (end to the back of the bend)”, choose the “Conduit” and “Trade size”, and leave “Take-up” on “Hand-bender table” or pick “Enter my bender’s take-up”. Back-to-back also needs the “Back-to-back length (outside to outside)”.
  6. Under “More options”, “Constants” switches offsets and saddles between “Bender chart (rounded)” and “Exact trigonometry”.
  7. Read the marks table: each row gives the distance from the end, the bend angle and the symbol to line up with.

The example buttons above the form, such as “Box offset 1/2 in at 10°”, load a full setup. “Copy result”, “Copy link” (a link that reopens the same inputs) and “Print / save as PDF” keep the marks; “Reset” restores the defaults.

How to calculate a conduit bend?

For an offset, multiply the offset height by the multiplier for the bend angle to get the distance between the two bends, and by the shrink factor to get how much shorter the run becomes. The multiplier is 1 ÷ sin of the angle (2 at 30°), and exact shrink per inch is tan of half the angle.

A 6 in offset gives these figures, rounded chart constants first and exact trigonometry second:

AngleBetween bends (chart)Shrink (chart)Between bends (exact)Shrink (exact)
10°36 in0.375 in34.553 in0.52493 in
22.5°15.6 in1.125 in15.679 in1.1935 in
30°12 in1.5 in12 in1.6077 in
45°8.4 in2.25 in8.4853 in2.4853 in
60°7.2 in3 in6.9282 in3.4641 in

Measured to the first bend at 12 in, the 30° offset puts mark 1 at 12 in and mark 2 at 24 in, with the conduit rolled 180° for the second bend. Measured to an obstruction 20 in away, a 6 in offset at 45° puts mark 2 at 20 + 2.25 = 22.25 in and mark 1 at 13.85 in.

How do I bend a 3-point saddle?

A 3-point saddle has a centre bend of 45° and two outer bends of 22.5° (or 60° with 30° outer bends). Mark the centre at the distance to the obstruction’s centre plus the shrink, then place the outer marks the same distance either side. Bend the centre first, then both outer bends in the same plane.

For a 2 in obstruction whose centre is 20 in from the end, with a 45° centre bend:

  1. Chart constants: 2.5 from the centre and 0.1875 in of shrink per inch of height.
  2. Centre mark = 20 + 2 × 0.1875 = 20.375 in, lined up with the centre-of-bend notch.
  3. Outer marks: 2 × 2.5 = 5 in each side, at 15.375 in and 25.375 in.
  4. The whole run shrinks by 0.75 in.

How do I calculate a 90-degree stub-up mark?

Subtract the bender’s take-up from the stub height you want, measured from the conduit end to the back of the bend. Put the mark at that distance and line it up with the arrow, hook toward the free end. A 10 in stub in 1/2 in EMT, with a 5 in take-up, is marked at 5 in.

The hand-bender take-up values the tool uses (from the Klein Tools guide) are:

Conduit1/2 in3/4 in1 in1-1/4 in
EMT5 in6 in8 in11 in
Rigid / IMC6 in8 in11 innot listed

The marking on your own bender head governs, which is why the tool lets you enter its take-up.

Worked examples

InputResult
6 in offset at 30°12 in between bends, shrink 1.5 in
6 in offset at 45°8.4 in (≈ 8 3/8 in) between bends, shrink 2.25 in
2 in obstruction, 45° centre, centre 20 in from the endmarks at 15.375 in, 20.375 in, 25.375 in
4 in high × 6 in wide obstruction at 30°marks at 17 in, 25 in, 31 in, 39 in
12 in stub-up, 3/4 in EMTmark at 6 in

Calculated by the tool above; open it with the same values to see each step.

Questions, briefly answered

What is shrink and why does it matter?

Bending an offset or saddle sends part of the conduit along a diagonal, so the straight run ends up shorter than the conduit you marked; that difference is shrink. Add it to a measurement taken to an obstruction, or the offset will finish short of where you need it.

Are conduit shrink values exact?

The chart values are rounded. A 6 in offset at 30° shrinks 1.5 in with the chart constant and 1.6077 in with exact trigonometry; at 10° the chart’s 1/16 in per inch compares with about 0.087 in.

What is the multiplier for a 30-degree offset?

The multiplier at 30° is 2, so the distance between bends is twice the offset height. A 6 in offset puts the bends 12 in apart.

How does the back-to-back 90 mode work?

Mark the first 90° as a stub-up. From the back of that bend, measure the back-to-back length and line the second mark up with the star symbol. If the bender does not fit that way, the tool also gives the length minus take-up, used with the arrow and the hook facing the first bend.

How many inches do you deduct for a 90 degree bend?

With a standard hand bender, the deduct is 5 in for 1/2 in EMT, 6 in for 3/4 in EMT, 8 in for 1 in EMT and 11 in for 1-1/4 in EMT. Rigid and IMC need more for the same trade size.

How many bends can a conduit run have?

For EMT, the total of all bends between pull points may not exceed 360° (NEC 358.26). The tool warns about this when you choose 60° bends, which make pulling wire harder.