Calculators/Conduit offset

Conduit offset bending calculator

The distance between your bend marks, the multiplier behind it, and the shrink to take off the measurement — at any angle, not just the five on the bender.

The offset

How far the run has to move to clear the obstruction.

If you give this, we will tell you where the first mark goes with the shrink already taken off.

The marks

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Check the result against the job. This does the arithmetic from the values you enter. Building codes, span tables and material specifications vary by jurisdiction and by product, and the governing document is your approved drawings and your local code. Nothing you type here leaves your browser: the calculation runs on your device and we never receive it.

How this is checked. Every formula on this site runs from one shared calculation engine, and every one has a test fixture whose expected answer was worked out from the geometry or taken from a figure the trade already publishes — never from what the code returns. Some land exactly, which is the point: a 6/12 hip over a 144″ run is exactly 216″, a 45° crown in a square corner bevels at exactly 30°, and a 30° conduit bend has a multiplier of exactly 2. Where a number is a convention rather than arithmetic — a code limit, a waste allowance, bundles per square — it is an input with a stated default rather than a hidden constant. Found something wrong? Tell us at [email protected] and we will fix it and say so.

The multiplier is just 1 ÷ sin

An offset is a right triangle. The offset height is the opposite side, the distance between your bends is the hypotenuse, so the hypotenuse is the height divided by the sine of the angle. Everything on the bender's table is that one division.

  • 10° — multiplier 6.0
  • 22.5° — multiplier 2.6
  • 30° — multiplier 2.0, because sin 30° is exactly ½
  • 45° — multiplier 1.4
  • 60° — multiplier 1.2

Thirty degrees survives as the default for a reason that has nothing to do with geometry: doubling a number is the easiest arithmetic there is to do accurately on a ladder.

Shrink is the part that gets forgotten

Going over an obstruction and back means travelling diagonally rather than straight, so the run comes up short at the far end. That loss is the shrink, and if you do not allow for it the box you were aiming at ends up out of reach.

Roughly a quarter inch per inch of offset at 30°, three eighths at 45°, a half at 60°. The steeper the bend, the more you lose — which is the real argument for shallower angles when you have the room for them.

Bend to the marks, not to the tape. These figures are centre-line geometry. Which mark on the bender you line up with — arrow, star or tear-drop — is a property of your bender, not of the maths, and getting that wrong shifts every bend by the same amount in the same direction.

Common questions

What is the multiplier for a 30 degree offset?

Two. The multiplier is one divided by the sine of the bend angle, and the sine of 30 degrees is exactly one half. So a 6 inch offset bent at 30 degrees puts the marks 12 inches apart. The other common multipliers are 2.6 at 22.5 degrees, 1.4 at 45 and 1.2 at 60.

What is shrink in conduit bending?

The amount the conduit gets shorter overall because it travels diagonally through the offset instead of straight. It is the travel minus the horizontal run it covers. At 30 degrees shrink is about a quarter inch for every inch of offset, at 45 about three eighths, and at 60 about a half.

Which offset angle should you use?

Shallower angles pull easier and shrink less, steeper angles clear an obstruction in a shorter distance. Thirty degrees is the usual compromise because its multiplier is exactly two, which is the easiest number to do in your head on a ladder.

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