What Is the Deduct on a Conduit Bend Chart?
A 90 degree bend does not start at your mark. The conduit curves through the bend, so the arrow on the bender has to sit back from the finished height by a fixed amount. That amount is the deduct. Get it right and your stub stands exactly where the print calls for; get it wrong and every stub on the job is off by the same inch or two.
What is the deduct on a conduit bender?
The deduct, or take-up, is the distance from the back of the 90 degree bend to the bender's arrow. You subtract it from the desired stub height to find where to place the arrow. It is set by the bender's radius, so each shoe size has its own deduct, printed on the tool: roughly 5, 6, 8 and 11.5 inches for 1/2, 3/4, 1 and 1.25 inch benders.
Think of the deduct as the bend eating into your measurement. If you want a stub 12 inches tall with a 3/4 inch bender, you place the arrow at 6 inches, because 12 minus 6 is 6. The bend curves up and the back of the stub reaches 12 inches. The number is constant for a given bender, which is why crews memorize their own tool's deducts.
What are the standard deduct values?
Standard hand-bender deducts are about 5 inches for 1/2 inch EMT, 6 inches for 3/4 inch, 8 inches for 1 inch, and 11.5 inches for 1.25 inch conduit. These match common Klein and Ideal benders. Always read the figure stamped on your own shoe, since radius varies slightly by manufacturer and the printed number is the one that lands the stub.
| Conduit size | Typical deduct (take-up) |
|---|---|
| 1/2 inch EMT | 5 in |
| 3/4 inch EMT | 6 in |
| 1 inch EMT | 8 in |
| 1.25 inch EMT | 11.5 in |
These values assume a standard radius bender. Specialty large-radius shoes change them, so confirm against your tool. The deduct stays the same whether the stub is 6 inches or 60 inches tall, because the bend geometry does not change with stub height.
How do you use the deduct to bend a 90?
Measure the finished stub height you need, subtract the deduct for your bender, and mark the conduit at that point. Line the bender arrow up with the mark, keep the conduit flat on the floor, and pull a full 90 degrees against the bender's degree marks. The back of the stub will reach your target height.
For a 10 inch stub with a 1/2 inch bender, mark at 5 inches, set the arrow there, and bend. Press the conduit down with steady foot pressure over the foot pedal so it hugs the shoe and does not kink. A dog-leg or under-bend means the conduit lifted off the shoe partway through, so keep weight on the heel until the leg stands plumb.
Why is the deduct different from the take-up sometimes?
Deduct and take-up describe the same distance and are used interchangeably by most electricians. Confusion creeps in because some manuals reserve take-up for the 90 degree subtraction and use deduct loosely for other bends. For a stub-up, treat them as one number: the amount you subtract from the desired height to set the arrow.
The words diverge only in older texts. Benfield's method calls the 90 degree value the take-up, while many bender castings stamp it as deduct. Either way it is the radius-driven distance the bend consumes. When a coworker or a chart uses one term, you can safely read it as the other for stub-up work.
Key takeaways
- The deduct is the distance from the back of a 90 to the bender arrow.
- It is set by bender radius, not conduit length, and is stamped on the shoe.
- Typical EMT deducts: 5, 6, 8 and 11.5 inches for 1/2, 3/4, 1 and 1.25 inch.
- Subtract the deduct from the desired stub height to place your mark.
- Deduct and take-up mean the same distance for a stub-up.
Frequently asked questions
- Does the deduct change with stub height?
- No. The deduct is fixed by the bender's radius, so it is the same whether you bend a 6 inch stub or a 50 inch one. You always subtract the same number from the desired height to find the mark. Only switching to a different bender size or a large-radius shoe changes the deduct you use.
- Why is my stub an inch too short?
- The most common cause is using the wrong deduct for the bender, or under-bending past or short of a true 90 degrees. Confirm the deduct stamped on your shoe, measure the finished bend with a level to verify it is a full 90, and keep the conduit pressed flat on the shoe through the whole pull so it does not spring back.
- Is the deduct the same for IMC and rigid?
- No. IMC and rigid conduit use benders with different radii than EMT, so their deducts differ even at the same trade size. Use the take-up figure for the specific bender and conduit type you are running. A calculator that lets you pick the conduit material keeps you from mixing EMT numbers into a rigid pull.
- Can I just memorize the deducts?
- Many electricians memorize the four common EMT deducts because they bend those sizes daily. It works until you switch tools or move to IMC, rigid, or large-radius benders, where the numbers change. Keeping a chart or app handy covers the sizes you bend less often and prevents a wrong-number stub on an unfamiliar tool.
Conduit Bending & NEC Reference, BigBalli. We turn the formulas in Benfield and Ugly's Electrical References into quick, checkable field math.
BendMarks is a teaching and estimation tool, not a substitute for licensed professional judgment or the National Electrical Code. Verify every deduct against the figure stamped on your own bender before you pull.