What the result means
An offset is two equal bends in opposite directions that move the conduit sideways around an obstruction. The distance between your two marks sets the depth of the offset, and the angle sets how long it is.
The shrink tells you how much the conduit shortens. When bending toward an obstruction, add the shrink to your first measurement. When bending away, you can often ignore it.
How it's calculated
- Distance between bends = offset ÷ sin(angle)
- Shrink = offset × tan(angle ÷ 2)
- Field rule distance = offset × multiplier
- Field rule shrink = offset × shrink per inch
Worked example
Clearing a 6 in obstruction with 30° bends.
- 6 ÷ sin 30° = 12.00 in between marks
- 6 × tan 15° = 1.61 in shrink (field rule 1.50 in)
Place marks 12 in apart; the conduit comes up about 1-5/8 in short.
Reference table
The values below are computed from the same calculator functions used above. They let you compare common sizes and operating points without replacing the interactive calculation or its assumptions.
| Angle | Multiplier | Marks for 6 in offset | Shrink |
|---|---|---|---|
| 10° | 6 | 36.00 in | 0.38 in |
| 22.5° | 2.6 | 15.60 in | 1.13 in |
| 30° | 2 | 12.00 in | 1.50 in |
| 45° | 1.4 | 8.40 in | 2.25 in |
| 60° | 1.2 | 7.20 in | 3.00 in |
Offsets only. Use the conduit bending calculator for saddles and 90-degree stubs.
Sources and assumptions
The listed formulas use the assumptions shown in the worked example. Calculator formulas are published with their units so a technician can check a result instead of treating it as a black box.
Last reviewed . Spot an error? Email support@tiermenu.com.
FAQ
What is the multiplier for a 45° offset?
1.4 is the common field rule; the trigonometric estimate is 1 ÷ sin 45° ≈ 1.414. Actual marks can vary with bending technique and tool.
When can I ignore shrink?
When you bend away from a fixed point, shrink moves the free end and usually doesn't matter. Toward an obstruction, it does.
Why is 10° so long?
Shallow angles need more distance to reach the same depth; the multiplier is 6.
Is this the same math as the conduit bending calculator?
Yes. It uses the same functions, focused on offsets only.
Using a reference result in the field
A calculator is most useful when the inputs match the job being checked. Confirm the conduit type and size, the bend angle and the point each measurement is taken from. The unit label beside the result is part of the result; do not carry a number into another calculation without checking its units.
Reference rows are provided for comparison, not as universal design limits. They use the values and conditions stated with each table. A different bender or conduit type can change take-up, shrink and where a bend lands in the field. Where the page calls out a code check, equipment rating or manufacturer table, that check remains part of the job.
Use the interactive inputs for the exact conditions at hand, then review the displayed formula and assumptions. If a value looks unexpected, change one input at a time and compare it with a known point in the reference table. Keep the measured readings and job-specific notes with the work record so another technician can understand how the result was obtained.
TierMenu provides these free calculators without an email gate. The results stay in this browser unless you choose to copy a shareable URL or print the page. A shared URL includes the calculator inputs in its query string; do not put personal or sensitive information in calculator fields.