What is the formula for bending conduit?

Bending conduit runs on two formulas. For 90s: mark at stub length minus take-up, with take-up being 5, 6, or 8 inches for half, three quarter, and 1 inch EMT.

For offsets: distance between marks equals obstacle depth times the multiplier, and the multiplier is the cosecant of the bend angle. At 30 degrees it is exactly 2, which is why 30 degree offsets dominate; the mental math is doubling.

Shrink matters too: every offset pulls the conduit back toward you, about a quarter inch per inch of depth at 30 degrees.

The NEC adds one constraint on top: no more than 360 total degrees of bend between pull points.

The conduit bending calculator runs the multipliers, shrink, and deducts for every angle and size.