Conduit bending calculator
Enter the obstacle height or the distances you need, and get your bend marks with the shrink worked out, to the nearest 1/16".
- Offsets at 10°, 22.5°, 30°, 45° or 60°
- 3-point saddles, 45° centre and 22.5° sides
- Kicks and back-to-back 90s
Type fractions the way you'd say them: 6 1/2, 6-1/2 or 6.5 all work.
Offset multipliers and shrink
Multiply the obstacle height by the multiplier to get the distance between your two marks. Shrink is how much the offset shortens the run, per inch of height.
| Bend angle | Multiplier | Shrink per inch | Rule of thumb |
|---|---|---|---|
| 10° | 5.759 | 0.087" | 1/16" |
| 22.5° | 2.613 | 0.199" | 3/16" |
| 30° | 2.000 | 0.268" | 1/4" |
| 45° | 1.414 | 0.414" | 3/8" |
| 60° | 1.155 | 0.577" | 1/2" |
- The multiplier is 1 ÷ sin(angle). Exact shrink per inch is tan(angle ÷ 2).
- The calculator uses the exact figures, so its shrink can differ from the rule of thumb by a 1/16" or so on bigger offsets.
Offset chart: distance between marks
Common obstacle heights at the four usual offset angles, in inches to the nearest 1/16.
| Height (in) | 10° | 22.5° | 30° | 45° |
|---|---|---|---|---|
| 2 | 11 1/2 | 5 1/4 | 4 | 2 13/16 |
| 3 | 17 1/4 | 7 13/16 | 6 | 4 1/4 |
| 4 | 23 1/16 | 10 7/16 | 8 | 5 11/16 |
| 6 | 34 9/16 | 15 11/16 | 12 | 8 1/2 |
| 8 | 46 1/16 | 20 7/8 | 16 | 11 5/16 |
| 10 | 57 9/16 | 26 1/8 | 20 | 14 1/8 |
| 12 | 69 1/8 | 31 3/8 | 24 | 17 |
How to lay out the bends
Offset
- Measure the obstacle height. That's the rise of the offset.
- Pick an angle and multiply the height by its multiplier. That's the distance between your two marks.
- If the offset has to finish at an exact spot, add the shrink to your measurement from the end of the conduit.
- Bend at the first mark, roll the conduit 180°, then bend at the second mark to the same angle, keeping both bends in line.
3-point saddle
- Measure to the centre of the obstacle and add the shrink, about 3/16" per inch of height. That's your centre mark.
- Measure out from the centre mark both ways by about 2.6 times the height for the side marks.
- Bend 45° at the centre mark, using your bender's saddle mark (often a notch or teardrop).
- Bend 22.5° at each side mark, the other way, to bring the conduit back down level.
Questions
What's the multiplier for a 30° offset?
2. The marks are twice the obstacle height apart. For 22.5° it's 2.6, for 45° it's 1.4 and for 10° it's about 6.
How much shrink should I allow per inch?
About 1/4" per inch of height for a 30° offset, 3/8" for 45° and 3/16" for 22.5°. The calculator works out the exact figure for your height and angle.
What is take-up, and what number do I use?
Take-up is how much of the stub the 90° bend uses. It comes from your bender and is usually stamped on it. Many hand benders use 5" for 1/2" EMT, 6" for 3/4" and 8" for 1", but check yours.
Why are the saddle side marks 2.6 times the height, not 2.5?
2.5 is the rule of thumb. The exact figure for 22.5° side bends is 2.613, which works out to nearly 1/2" more on a 4" obstacle.
Does this work for rigid or IMC?
Yes, the geometry is the same for any conduit. Take-up and gain depend on the bender and the conduit size, so use your bender's figures for those.
Does it do metric?
This page works in inches. The Electrician Toolbox app also works in centimetres.
Bend marks in your pocket.
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