Conduit Bending Calculator
Calculate the distance between bends and conduit shrink for an offset bend, from the offset distance and bend angle.
How this calculator works
When you bend an offset into a piece of conduit — to get around a beam, duct, or another obstruction — the conduit no longer runs in a straight line between its two ends. That bend pulls some length out of the run, which is why you need to know two things before you cut: how far apart to place the two bend marks, and how much extra length to add so the finished piece still reaches where it needs to.
Formula: Distance between bends = offset ÷ sin(bend angle). Shrink = offset × shrink constant for that angle (10° = 6, 22.5° = 2.6, 30° = 2, 45° = 1.4, 60° = 1.2).
Worked example
A 4-inch offset bent at a 30° angle:
- Distance between bends: 4 ÷ sin(30°) = 8 in
- Shrink: 4 × 2 = 8 in
That means the two bend marks on the conduit go 8 inches apart, and the conduit should be cut 8 inches longer than the straight-line distance it needs to cover.
Notes
Shrink means the conduit’s overall end-to-end length is shorter than it was before bending, so you measure the straight-line distance you need to cover first, then cut the conduit longer than that by the shrink amount before you start bending.
30° and 45° are the most common offset angles electricians use in the field, since most conduit benders are marked for these angles and they strike a practical balance between how gradual the offset is and how much space it takes up.
How to use
Enter the offset distance — how far the conduit needs to shift sideways to clear the obstruction — and pick the bend angle you plan to use. The calculator returns the distance to mark between your two bends and how much extra length to add to your cut for shrink.
Electrical work is code-governed and safety-critical. Confirm circuit, conductor, and equipment sizing with a licensed electrician and your local code.
Frequently asked questions
What is conduit shrink?
Shrink is how much shorter a piece of conduit ends up, end-to-end, after you bend an offset into it. Bending pulls the conduit out of a straight line, so the overall length between its two ends is less than it was before you bent it. You compensate by cutting the conduit longer than the straight-line run by the shrink amount.
How do I find the distance between bends?
Divide the offset distance (how far you need the conduit to shift sideways) by the sine of the bend angle you're using. For example, a 4-inch offset at 30 degrees gives 4 ÷ sin(30°), or 8 inches between the centers of the two bends.
Which bend angle should I use?
30° and 45° are the two most common offset angles electricians use. 30° gives a gentler, longer offset that's easier to pull wire through; 45° is more compact but pulls harder. Shallower angles like 10° or 22.5° are used when you need a very gradual shift over a longer distance.
Does the shrink amount change with the angle?
Yes. Shrink is the offset distance multiplied by a constant that depends on the bend angle: roughly 6 for 10°, 2.6 for 22.5°, 2 for 30°, 1.4 for 45°, and 1.2 for 60°. Shallower angles shrink the conduit more per inch of offset than steeper ones.
Estimates only. Verify quantities with your supplier before purchasing.