Bending conduit accurately comes down to a few trigonometric relationships built into every hand bender. This calculator gives you the gain, take-up, and mark-to-bend dimensions for the everyday bends — stub-ups, offsets, saddles, and back-to-back — so you can lay out a run without re-deriving the math on the deck.
Bend types and when to use them
Stub-up (90-degree bend) — the most common bend, bringing conduit out of a floor or up a wall to a panel or box. Accuracy matters because the stub height sets where the end of the conduit lands.
Two-point offset — used to dodge an obstacle in the path of a straight run (a beam, another pipe, or a structural member). Two equal-angle bends in opposite directions displace the run sideways or vertically while keeping the conduit parallel to its original path.
Three-point saddle — used to cross over a round obstacle (another conduit, a pipe) without using fittings. The center bend is the largest (typically 45°) and sits directly over the obstacle; the two outer bends (typically 22.5°) restore the original path.
Back-to-back (U-bend) — two 90-degree bends facing the same direction, forming a U-shape. Used to carry conduit around a corner with two parallel stubs.
The mathematics behind the marks
The key relationships, where the offset angle drives the geometry:
offset multiplier = 1 ÷ sin(angle)
distance between marks = offset height × multiplier
shrink per inch = (1 ÷ sin(angle)) − (1 ÷ tan(angle)) (cosecant minus cotangent)
total shrink = offset height × shrink-per-inch
stub mark-to-bend = stub height − take-up
saddle side marks = center ± 2.5 × obstruction height (45° center)Quick-reference multiplier and shrink table
| Bend angle | Offset multiplier | Shrink (in/in of offset) |
|---|---|---|
| 10° | 5.76 | 0.06 |
| 22.5° | 2.61 | 0.22 |
| 30° | 2.00 | 0.25 |
| 45° | 1.41 | 0.41 |
| 60° | 1.15 | 0.57 |
These are the values you find stamped on most hand benders. The calculator computes them exactly from the trigonometry, but these rounded values work for field use.
Take-up by conduit size
Take-up is the length the 90-degree bend consumes, determined by the conduit size and bender shoe. Common values for EMT:
| Conduit size | Approx. take-up |
|---|---|
| 1/2 in | 5 in |
| 3/4 in | 6 in |
| 1 in | 8 in |
| 1-1/4 in | 11 in |
Subtracting take-up from the desired stub height tells you where to set the arrow mark from the free end of the conduit.
Worked examples
30° two-point offset, 6 in obstruction.
- Distance between marks: 6 × 2.00 = 12 in
- Total shrink: 6 × 0.25 = 1.5 in (shift first mark 1.5 in toward the bender end)
10 in stub-up in 1/2 in EMT.
- Mark-to-bend: 10 − 5 (take-up) = 5 in from the free end
45° saddle over a 4 in pipe.
- Center mark: directly over the obstruction
- Side marks: 2.5 × 4 = 10 in on each side of center
- Shrink: approximately 4 × 0.41 = 1.6 in to add to the run
Practical tips
- Always bend a test piece first to verify that your bender’s take-up matches the rated value — shoe wear, technique, and conduit material all affect the actual result.
- Mark with a pencil or marker before bending — erasing and re-marking is far cheaper than a wasted stick of conduit.
- Conduit type matters. EMT (thin-wall) and rigid (IMC, RMC) have slightly different bending radii and take-up values. Use the value rated for your specific conduit type.
- Keep foot pressure even on the bender throughout the stroke for consistent bend angles. Rocking the bender or losing foot contact skews the angle.