Arrowmark › Offset multiplier chart
Conduit offset multiplier chart
To bend an offset, multiply the rise by the angle's multiplier to get the distance between bends, and add the shrink to your first mark. Here are both numbers for every common angle — exact, and the way charts round them.
| Angle | Multiplier | Chart value | Shrink per inch of rise | Nearest 1/16" |
|---|---|---|---|---|
| 5° | 11.474 | 11.5 | 0.044" | 1/16" |
| 10° | 5.759 | 5.8 | 0.087" | 1/16" |
| 15° | 3.864 | 3.9 | 0.132" | 1/8" |
| 22.5° | 2.613 | 2.6 | 0.199" | 3/16" |
| 30° | 2.000 | 2.0 | 0.268" | 1/4" |
| 45° | 1.414 | 1.4 | 0.414" | 7/16" |
| 60° | 1.155 | 1.2 | 0.577" | 9/16" |
Multiplier = 1 ÷ sin(angle), the cosecant. Shrink = tan(angle ÷ 2) per inch of rise. These are the same formulas Arrowmark uses in its multiplier mode.
How to use the chart
Example: 30° offset, 8" rise. Distance between bends = 8 × 2 = 16". Shrink = 8 × 0.268 = 2.14", about 2 1/8". If the obstruction starts 40" from the end of the pipe, put the first mark at 40 + 2 1/8 = 42 1/8" and the second mark 16" from the first, then bend both to 30° in opposite directions.
- Smaller angles (10°, 15°, 22.5°) give a longer, gentler offset with less shrink — easier to pull wire through.
- Larger angles (45°, 60°) fit a tight space but shrink more and are harder on the wire pull.
- Most electricians default to 30° because the multiplier is a clean 2.
Why printed charts disagree
Charts round. The 45° shrink is 0.414" per inch: many charts print 3/8", the nearest sixteenth is 7/16". The 10° multiplier is 5.76, often printed as 6. Over a 10" rise the 45° shrink rounding moves the first mark almost 3/8", and using 6 for a 10° offset puts the marks about 2 7/16" too far apart. When the number matters, use the exact value — or the offset calculator, which does it to the 1/16".
The multiplier ignores your bender. A real shoe bends around a radius, so the true distance between bends is a little shorter than the chart says. For a 30° offset with an 8" rise on a Klein ¾" EMT hand bender, Arrowmark gives 15 15/16", not 16" — and shows why on screen. Pick your bender in Arrowmark and every mark comes from that shoe's radius and deduct.
Common questions
What is the multiplier for a 30 degree offset?
The multiplier for a 30° offset is 2. Multiply the offset depth (rise) by 2 to get the distance between the two bends: a 6" rise needs marks 12" apart. Each inch of rise shrinks the run by about 1/4" (0.268").
What is the multiplier for a 45 degree offset?
The multiplier for a 45° offset is 1.414, usually rounded to 1.4. A 10" rise needs marks about 14 1/8" apart. Shrink is 0.414" per inch of rise — charts round it to 3/8", the nearest sixteenth is 7/16".
What is the multiplier for a 22.5 degree offset?
The multiplier for a 22.5° offset is 2.613, usually rounded to 2.6. A 4" rise needs marks about 10 7/16" apart, with about 3/16" of shrink per inch of rise.
How do you calculate shrink on a conduit offset?
Shrink equals the rise times tan(angle ÷ 2). For a 30° offset that is 0.268 per inch, so an 8" rise shrinks the run by 2 1/8". Add the shrink to the measurement to the obstruction when you place the first mark.