What the result means
Every bend in conduit is geometry. The calculator shows the exact numbers from trigonometry alongside the field rules printed on most benders, so you can see how close the quick method gets.
Shrink is how much shorter the conduit gets in the direction of travel when you bend an offset or saddle. Add it to your measurement to the obstruction so the bend lands where you need it.
How it's calculated
- Offset distance between bends = offset ÷ sin(angle)
- Offset shrink = offset × tan(angle ÷ 2)
- 3-point saddle: outer marks = 2.5 × height from center; shrink = 3/16 in per inch (field rule)
- 4-point saddle: two offsets separated by the obstruction width
- 90° stub mark = stub height − take-up
Field multipliers: 10° 6.0, 22.5° 2.6, 30° 2.0, 45° 1.4, 60° 1.2. Field shrink per inch: 1/16, 3/16, 1/4, 3/8, 1/2 in.
EMT hand bender take-up defaults: 1/2 in = 5 in, 3/4 in = 6 in, 1 in = 8 in, 1-1/4 in = 11 in. Check the markings on your bender.
Worked example
A 6 in offset using 30° bends.
- Distance = 6 ÷ sin 30° = 12.00 in
- Exact shrink = 6 × tan 15° = 1.61 in (1-5/8)
- Field rule: 6 × 2.0 = 12 in; shrink 6 × 1/4 = 1.50 in
Mark 12 in apart and add about 1-5/8 in to the measurement to the obstruction.
Reference table
The values below are computed from the same calculator functions used above. They let you compare common sizes and operating points without replacing the interactive calculation or its assumptions.
| Angle | Multiplier | Shrink per inch | EMT take-up examples |
|---|---|---|---|
| 10° | 6 | 0.063 in | 1/2 in: 5 in; 3/4 in: 6 in; 1 in: 8 in; 1-1/4 in: 11 in |
| 22.5° | 2.6 | 0.188 in | 1/2 in: 5 in; 3/4 in: 6 in; 1 in: 8 in; 1-1/4 in: 11 in |
| 30° | 2 | 0.250 in | 1/2 in: 5 in; 3/4 in: 6 in; 1 in: 8 in; 1-1/4 in: 11 in |
| 45° | 1.4 | 0.375 in | 1/2 in: 5 in; 3/4 in: 6 in; 1 in: 8 in; 1-1/4 in: 11 in |
| 60° | 1.2 | 0.500 in | 1/2 in: 5 in; 3/4 in: 6 in; 1 in: 8 in; 1-1/4 in: 11 in |
Reference values are examples based on the stated assumptions. Verify manufacturer data, conductor ampacity and local requirements before using a result.
Sources and assumptions
Field multipliers: 10° 6.0, 22.5° 2.6, 30° 2.0, 45° 1.4, 60° 1.2. Field shrink per inch: 1/16, 3/16, 1/4, 3/8, 1/2 in. EMT hand bender take-up defaults: 1/2 in = 5 in, 3/4 in = 6 in, 1 in = 8 in, 1-1/4 in = 11 in. Check the markings on your bender. Calculator formulas are published with their units so a technician can check a result instead of treating it as a black box. Where a code table, manufacturer specification or field measurement is required, use the applicable local source.
Last reviewed . Spot an error? Email support@tiermenu.com.
FAQ
Should I use exact or field-rule numbers?
Both land close for small offsets. For long runs or tight tolerances, exact numbers reduce cumulative error.
Why does my bender take-up differ?
Take-up varies by manufacturer and conduit type. The defaults here are typical EMT hand bender values; always check the markings on your bender.
What angle is best for offsets?
30° is common because the multiplier is 2 and the shrink is easy. Use shallower angles for easier wire pulls.
Does this work for rigid or PVC?
The geometry works for any conduit, but take-up and gain differ for rigid, IMC and PVC. Use your bender's data.
How many bends can I have between pull points?
Most codes limit the total to 360° between pull points. Count every offset and saddle bend.
Using a reference result in the field
A calculator is most useful when the inputs match the job being checked. Confirm the conduit type and size, the bend angle and the point each measurement is taken from. The unit label beside the result is part of the result; do not carry a number into another calculation without checking its units.
Reference rows are provided for comparison, not as universal design limits. They use the values and conditions stated with each table. A different bender or conduit type can change take-up, shrink and where a bend lands in the field. Where the page calls out a code check, equipment rating or manufacturer table, that check remains part of the job.
Use the interactive inputs for the exact conditions at hand, then review the displayed formula and assumptions. If a value looks unexpected, change one input at a time and compare it with a known point in the reference table. Keep the measured readings and job-specific notes with the work record so another technician can understand how the result was obtained.
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