Conduit Offset Calculator: Bend Spacing & Shrink

What an offset is and when you need one

Two equal bends, opposite directions, and the pipe carries on parallel to where it started — that's an offset. You bend one to clear a beam flange, step off a wall into a box, or jog around another pipe already in your way.

Two numbers decide the layout: the distance between bends (how much pipe runs on the angle) and the shrink (how much shorter the whole run gets, because part of that length went sideways instead of forward).

Conduit offset calculator

Distance between bends: 12"
Shrink: 1 19/32"
Multiplier: ×2.000

Showing the worked example. Turn on JavaScript to calculate your own numbers.

Same math as the app: distance between bends = depth ÷ sin(angle), shrink = depth × tan(angle ÷ 2). Two equal bends, and these are the five angles the app's Offset tool offers. Add the shrink when you measure to the first mark.

The conduit offset formula

Distance between bends = offset depth ÷ sin(angle). The 1 ÷ sin(angle) part is the multiplier, so in practice: depth × multiplier.
Shrink = offset depth × tan(angle ÷ 2). Charts list this per inch of offset, so in practice: depth × shrink per inch.

Conduit offset multiplier chart, with shrink

Values shown on PipeMaster's Bend Reference card
Bend angle	Multiplier	Shrink per inch of offset
10°	5.759	0.087
22.5°	2.613	0.199
30°	2.000	0.268
45°	1.414	0.414
60°	1.155	0.577

Shallow angles make a long, gentle offset that pulls easily but needs room. Steep angles fit tight spots but shrink more, and each offset adds twice its angle to the 360° total allowed between pull points. 30° is a popular middle ground because the multiplier is exactly 2.

How to calculate an offset in PipeMaster

Open Offset from the Calculators group on the main screen.
Under Bend Angle, tap 10.0°, 22.5°, 30.0°, 45.0° or 60.0°.
Tap the Offset Depth value to open the keypad. Type whole inches, a numerator and a denominator, or millimetres if Units is set to Millimeters.
Read Distance Between Bends and Shrink under Result. They update as you change the inputs.
Tap Save to keep the result in History.

Worked examples

PipeMaster results for common offsets
Offset Depth	Angle	Distance Between Bends	Shrink
6"	30°	12"	1 19/32"
4"	45°	5 21/32"	1 21/32"
3 1/2"	22.5°	9 5/32"	11/16"
4"	10°	23 1/32"	11/32"
4"	60°	4 5/8"	2 5/16"
100 mm	30°	200 mm	27 mm

Results are rounded to the nearest 1/32", or shown in whole millimetres in metric mode.

Where do the marks go on the pipe?

PipeMaster gives the spacing and the shrink, not the position of the first mark — that one depends on your own measurement. The usual layout: measure from the end of the conduit to the obstruction, add the shrink, and make the first mark there. Then measure the distance between bends back toward the end for the second mark.

Example: the obstruction starts 30" from the end and you want a 6" offset at 30°. First mark at 30" + 1 19/32" = 31 19/32", second mark 12" back, at 19 19/32".

What about 20° or another angle?

The Offset calculator only offers the five standard angles. For any other angle, open Bend Reference, set Custom Angle (1° to 89° in 0.5° steps) and read the Multiplier and Shrink/in for it. At 20° that is 2.924 and 0.176, so a 5" offset needs about 14 5/8" between bends and shrinks about 7/8"; do that multiplication by hand.

Common mistakes

Ignoring shrink when the offset must land at a fixed point, so the bend finishes short of the obstruction.
Bending the two halves at different angles: the conduit will not come out parallel.
Rotating the pipe between bends: both bends must sit in the same plane or you get a dog leg.
Measuring the depth from different faces: measure from the same side of the conduit to the same side of where it has to land.

Questions and answers

What is shrink in conduit bending?

It is the length an offset takes out of a straight run, because the conduit travels sideways over part of its length. Multiply the offset depth by the shrink per inch for your angle; at 30° that is 0.268, so a 6" offset shrinks 1 19/32".

What is the multiplier for a 45 degree offset?

1.414, with 0.414 of shrink per inch of offset. A 4" offset at 45° needs 5 21/32" between bends and shrinks 1 21/32".

Why does the 30° multiplier come out to exactly 2?

Because sin(30°) is 0.5, and the multiplier is 1 ÷ sin(angle). That is why many electricians default to 30°: doubling the depth is easy to do in your head.

Is there a free conduit bending app for iPhone?

Yes. PipeMaster costs nothing to download, and the offset screen described on this page works without paying, as do the stub-up screen and the multiplier card; the free version shows ads. The other bends and the electrical tools come with the optional Pro upgrade.

Rolling offset in conduit: the formula, the roll angle and the marks · PipeMaster
How to bend a 3-point and a 4-point saddle over an obstruction · PipeMaster
How to bend a 90 in EMT conduit: stub-up mark, deduct and gain · PipeMaster
How does a hand bender app track deduct and take-up for each tool? · PipeMaster