Conduit Offset Calculator

By Blissom · Updated 2026-10-23

Layout values: check them against your own bender, on scrap first.

How to use the offset calculator

1. Work out the depth. Depth is how far the conduit's centerline has to move, measured square to the run. When you are clearing something, take the obstruction's outermost face, add the clearance you want and half the conduit's outside diameter to get the new centerline, then subtract where the centerline is now. Do not use the obstruction's projection alone.
2. Pick the angle. 30° for most jobs. The calculator shows the distance between bends and the shrink instantly. Add the required completion position (how far from your starting end, measured along the straight line of the run, the offset has to be complete) and it also places both marks from that end.
3. Mark and bend. Measure the spacing between the two marks on the straight conduit. Put the bender arrow on the first mark and bend, rotate the conduit exactly 180°, then put the arrow on the second mark and bend to the same angle (the arrow-to-arrow method most hand-bender guides use for offsets).
4. Sight it. Look down the conduit. Both bends must sit in the same plane, or the offset "dog-legs" and will not lie flat.

Worked example: clearing a pipe with a 30° offset

You are running 1/2" EMT (0.706" outside diameter) flat on a wall. A water pipe stands 3-1/2" off the wall, and its near side is 40" from the end of your stick. You want 1/2" of clearance over it.

1. New centerline: 3-1/2" + 1/2" clearance + 0.353" (half the EMT diameter) = 4.353" from the wall. The centerline is now 0.353" off the wall, so the depth is 4".
2. Pick the completion position: the conduit should be up at full height before it reaches the pipe, so try 38".
3. Spacing: 4 × 2 = 8" between marks. Estimated shrink: 4 × 1/4" = 1".
4. Second mark = completion point + shrink = 39". First mark = 39 − 8 = 31".
5. Bend 30° with the arrow on 31", rotate 180°, bend 30° with the arrow on 39".

In the ideal sharp-corner model the offset reaches its new height at about 31 + 8 × cos 30° = 37.9". A real bend has a radius, so this does not guarantee clearance before the pipe at 40": the second bend's curve ends past that point, and how far depends on the shoe. Check where the second bend actually ends and where the conduit's outside edge passes the pipe, using your bender's dimensions or a test bend on scrap, and move the completion position earlier if the clearance is not there. The exact shrink for 4" at 30° is 1.07" against the field 1"; the formulas page shows where each number comes from.

Offset multiplier and shrink chart

The left columns are the trade constants printed on hand benders and in bender guides; the right columns are the exact trigonometry. The trade numbers are convenient field values, not always ordinary roundings: csc 10° is 5.759, but the trade uses 6.

Where the marks land for a fixed completion point

Call C the required completion position: how far from the starting end, along the straight line of the run, the offset has to be complete. Choose C short of the obstruction by the clearance and a margin for the rounded bends. In the ideal geometry the second mark goes at C plus the shrink and the first mark one bend spacing before it. The full depth-by-angle grid is on the bending chart.

These are theoretical field mark positions, not a guarantee that the bends can be made. The smallest workable depth depends on the bender's centerline radius, the conduit size and the shoe clearance; cells marked check bender are shallower than two separate bends can reach on a 1/2" EMT shoe with a 4-5/8" radius (2 × radius × (1 − cos θ): about 1-1/4" at 30° and 2-3/4" at 45°), and larger shoes need more.

Example: a 3" offset at 30° that must be finished at C = 50" puts the marks at 50 − 5-1/4 = 44-3/4" and 50 + 3/4 = 50-3/4". When the offset has to start at a fixed point instead, put the first mark there; the marks need no shrink correction, but anything measured beyond the offset comes up short by the shrink.

Which angle should you use?

• 10° for box offsets and shallow moves under about 1". Marks are far apart (6 × depth), shrink is almost nothing.
• 22.5° for small offsets when you want an easy pull; the marks are 2.6 × depth apart.
• 30° for almost everything. The multiplier of 2 is easy to do in your head and the shrink is modest.
• 45° when the offset has to happen in a short space. Expect 3/8" of shrink per inch and a harder pull.
• 60° only when nothing else fits. 1/2" of shrink per inch, and each 60° bend counts heavily toward the 360° limit between pull points.

The NEC limits the total bends between pull points to 360° (NEC 2023 358.24(B) for EMT (358.26 in the 2020 and earlier editions); the 2026 NEC adds 300.24 for runs that combine raceway types; follow the edition your jurisdiction has adopted). An offset at 30° uses 60° of that, at 45° 90°, at 60° 120°. For PVC, which is heat-bent rather than bent in a hand bender, see how to bend PVC; for rigid, how to bend rigid conduit.

The offset formula

These are the ideal centerline formulas, treating each bend as a sharp corner. The straight run between the two corners is the hypotenuse of a right triangle whose short side is the depth, so its length is depth ÷ sin θ. Shrink is that length minus the distance it covers along the run, which simplifies to depth × tan(θ ÷ 2). Real bends have a radius, bender reference marks and spring-back, so treat results as layout values and check them on the conduit. The trade multipliers are simplified constants rather than exact roundings (10° is used as 6, not 5.76).

Mistakes that ruin offsets

• Not rotating exactly 180° between the bends. A few degrees off and the offset dog-legs. Sight down the pipe before the second bend and check that the first bend points straight at you.
• Unequal angles. A 30° and a 32° bend leave the conduit crooked on the far side. Use the marks on the bender or a level.
• Forgetting the shrink when the offset must be finished at a fixed point: the offset lands short and hits the obstruction.
• Using the obstruction's projection as the depth. Add the clearance and half the conduit diameter, measured centerline to centerline.
• Measuring the depth to different edges of the pipe at each end, which throws the depth off by a pipe diameter.
• Using the arrow on one bend and the star or notch on the other. Offsets use the same reference mark on the bender for both bends.

Sources: NEC 2023 358.24 and Chapter 9, Table 2; Klein Tools Conduit Bender Guide (stub take-up, offset multipliers and shrink, saddles). Method.

Questions electricians ask

Bend the offset, not the math

• Both marks measured from the end of the pipe, from your distance to the obstruction
• Corrected for the radius of your bender shoe
• Drawing with the hook direction for each mark, and guide mode one step at a time
• Rolling, parallel and matching offsets, saved jobs, PDF bend sheets, offline

Android only. There is no iPhone version yet; the free calculators on this site work on any phone.

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