Conduit bending calculator
Distance between marks and shrink for offsets, saddles, kicks and rolling offsets, plus stub-up marks. Uses the multipliers printed on your bender. Free, no signup.
Work out your bend marks
Part of Foster Tools: 7 pro calculators in one appOpen in app →How it’s calculated
Distance between bends = offset height × multiplier (1 ÷ sin of the angle); shrink = offset height × tan of half the angle. A 3-point saddle uses a 45° center and two 22.5° outer bends, with the outer marks 2.5 × the height from the center; add one half's shrink (3/16" per inch of height on bender charts) to the center-mark measurement, and the whole run shortens by twice that; a rolling offset bends to the true offset √(rise² + roll²); a 90° stub-up marks stub height − bender take-up.
Assumptions
- Bender chart mode uses the rounded multipliers and shrink printed on bender charts (10°: 6 and 1/16"; 22.5°: 2.6 and 3/16"; 30°: 2 and 1/4"; 45°: 1.4 and 3/8"; 60°: 1.2 and 1/2") and 2.5 for a 3-point saddle. Exact mode uses the trigonometry instead.
- Take-up (deduct) values are typical for hand benders. They differ between makes, especially above 1" (for example, Gardner Bender lists 12" for 1-1/4" EMT where this table shows 11"). Use the number stamped on your bender.
- Results are layout geometry. They don't account for springback or the bender's radius beyond the take-up.
Sources
Same code as our iPhone apps, tested against worked examples. Spot a mistake? Tell us and we’ll fix it. How we calculate
Conduit bend questions
How do you calculate a conduit offset?
Multiply the offset depth by the multiplier for your bend angle to get the distance between the two bend marks. At 30 degrees the multiplier is 2, so a 6 inch offset needs marks 12 inches apart. The pipe also shrinks, by 1/4 inch per inch of offset at 30 degrees, so add 1 1/2 inches to your first mark.
What are the multipliers for conduit bends?
The common bender chart values are: 10 degrees, multiplier 6 and 1/16 inch shrink per inch of offset; 22.5 degrees, 2.6 and 3/16 inch; 30 degrees, 2 and 1/4 inch; 45 degrees, 1.4 and 3/8 inch; 60 degrees, 1.2 and 1/2 inch. The exact values are 1 divided by the sine of the angle.
How do you bend a 3-point saddle?
A 3-point saddle uses a 45 degree center bend and two 22.5 degree outer bends. Put the center mark over the obstruction, then place the outer marks on each side at 2.5 times the obstruction height from the center mark. The calculator shows the marks and the shrink.
What is take-up on a 90 degree stub-up?
Take-up is the length the bender adds as it makes a 90 degree bend. Subtract it from the stub height you want and mark the pipe that far from the end, then line up the bender arrow with the mark. Typical hand-bender take-up is 5 inches for 1/2 inch EMT, 6 inches for 3/4 inch and 8 inches for 1 inch.
What is a rolling offset?
A rolling offset moves the pipe up and sideways at the same time. The true offset is the diagonal, the square root of rise squared plus roll squared. Bend it as a normal offset of the true offset, rotating the pipe in the bender by the roll angle between the two bends.
Guides
- How to Bend a Conduit Offset: Multipliers and Shrink
Distance between marks = offset depth × multiplier (30°: 2, 45°: 1.4). Shrink = depth × shrink per inch (30°: 1/4"). A 6" offset at 30° has marks 12" apart and 1 1/2" of shrink. - How to Bend a 3-Point Saddle
Center mark over the obstruction plus 3/16" shrink per inch of height; outer marks 2.5 × the height on each side. Bend 45° at the center and 22.5° at each outer mark.
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