How to Find the Angle of an Existing Offset
Quick answer
To match an existing offset, measure its height and the distance between its bend centers, then solve for the angle. By the multiplier method, sin(angle) = offset height ÷ distance between bend centers. An offset 6" high with 12" between bend centers was bent at 30.0° by the multiplier method, or 29.9° on a 1/2" EMT hand bender, which allows for the shoe’s radius.
Sometimes the offset you have to copy is already on the wall: a neighbor’s conduit, or one bent earlier with no note of the angle. Measure how high it is and how far apart its bends are, and the calculator works out the angle it was bent to.
What to measure
- Between bend centers: along the conduit, from the middle of one bend to the middle of the other.
- Offset height: how far the offset moves the conduit, center to center.
How to bend it
- Enter both measurements. The calculator gives the Bend angle, to 0.1°, and the shrink at that angle.
- Bend your offset to that angle from the marks shown, as on the Offset screen.
- If you need the marks measured from the conduit end, enter the same height and angle on the Offset screen with the distance.
Where the numbers come from
The Offset screen’s distance between bends is solved backwards for the angle. The angle is rounded to 0.1°, as close as anyone can bend, and the shrink and marks are worked out from the rounded angle.
between bend centers = height ÷ sin(angle) − g(angle)- Between bend centers
- 12"
- Offset height
- 6"
- Bend angle
- 29.9° (30.0° by multiplier)
- Shrink
- 1 1/2" (1 5/8" by multiplier)
If it turns orange or red
Red with no numbers means no angle up to 90° fits: the bends are too close together for that height. Otherwise the colors are the Offset screen’s at the solved angle: red means this shoe can’t bend a matching offset, and orange that it probably can’t, even if another bender managed it.
Get the marks for your bender
BendMate works this out from your bender’s radius and deduct, flags a bend that won’t work, and shows you every mark.
Common questions
How do you find the middle of a bend on conduit?
The middle of a bend is halfway along its curve. Mark where each curve starts and ends, and measure between the halfway points.
How precisely can you match an offset angle?
Round the angle to 0.1°, as close as anyone can bend, and work the shrink and marks out from the rounded angle. An offset 6" high with 12" between bend centers comes out at 29.9° and 1 1/2" of shrink on a 1/2" EMT hand bender.
What if no angle fits the offset I measured?
If the bends are too close together for the height, no angle up to 90° fits. Even when one does, your shoe may not be able to bend a matching offset at that angle, if its bends would run into each other or leave too little straight between them, even if another bender managed it.