Calculate bend radius, offsets, and bending multipliers for conduit runs. Get the measurements for accurate bends the first time.
Bending conduit accurately comes down to a few geometric relationships. An offset uses a multiplier based on the bend angle to find the distance between two bends. A saddle clears an obstacle with a set of three or four bends. A stub-up uses a take-up deduction so the finished height lands where you want it.
The calculator gives you the shrink, the distance between marks, and the deductions for common angles, so your bends come out right the first time without trial and error on the pipe.
For a 6 inch offset using 30 degree bends, the multiplier is 2, so your marks are 12 inches apart. The shrink for a 30 degree offset is about a quarter inch per inch of offset, so a 6 inch offset shrinks the run by roughly 1.5 inches, which you account for when you measure to the first mark.
Conduit bending is a workmanship practice rather than a numeric code table, but the total bends in a run are limited: no more than 360 degrees of bends between pull points, per NEC Article 358.26 for EMT and the corresponding CEC rules in Section 12. Minimum bend radius requirements also apply. The geometry here is trade math, not reproduced code.
The offset multiplier depends on the bend angle: about 2 for 30 degrees, 1.4 for 45 degrees, and 1.2 for 60 degrees. Multiply the offset depth by this factor to get the distance between your two bend marks.
Shrink is the amount a run shortens along its length when you put an offset in it. You account for shrink when measuring to the first bend so the conduit still reaches its destination.
No more than 360 degrees of total bends between pull points, which is the equivalent of four 90 degree bends. More than that makes the conductor pull too difficult.
Take-up is the distance from the end of the conduit to the centre of a 90 degree bend for a given bender and conduit size. You subtract it so the finished stub height is correct.