How to Use This Calculator
Bending conduit accurately is a core skill for electricians. An offset bend moves the conduit sideways (or up/down) to avoid an obstacle. A kick bend angles conduit upward or downward. A saddle bend (or three-bend saddle) goes over or under a pipe or duct. Each type uses trigonometry to calculate how much pipe travel is needed and how much the pipe “shrinks” (loses linear distance) due to the bends.
Enter the obstacle height (or lateral offset) and your desired bend angle (typically 22.5°, 30°, 45°, or 60°), and the calculator gives you the travel distance (how much pipe to mark for the bend), the run (the horizontal distance covered), and the shrink (how many inches of linear run the bends consume). The shrink value is critical: if you don’t account for it, your conduit will end up short.
Example: You’re making a 4-inch offset bend at 45 degrees. Travel = 4 ÷ sin(45°) ≈ 5.66 inches for each bend. Run = 4 ÷ tan(45°) = 4 inches. Shrink = 4 × (1/tan(45°) - 1/sin(45°)) or use the calculator’s shrink table directly. For a 45-degree offset, shrink ≈ 1.69 inches total.
Formula
Travel Distance (for first bend): Travel = offset / sin(angle)
Run Distance: Run = offset / tan(angle)
Shrink (linear distance lost to the bends): Shrink = 2 × offset × (1/tan(angle) - 1/sin(angle))
Or use standard shrink values:
- 22.5° offset: shrink ≈ 4.25× the offset
- 30° offset: shrink ≈ 2.73× the offset
- 45° offset: shrink ≈ 1.69× the offset
- 60° offset: shrink ≈ 0.73× the offset
Saddle Bend Deduct (for three-bend saddle): Deduct = 2× the obstacle height + rise (Use the bend deduct table for your angle; values are tabulated in trade references and bend charts)
When to Use This
Before you cut conduit and set up your bender. Measure carefully. An incorrect calculation means the conduit will be short (requiring a coupling and extra expense) or too long (requiring rework). Experienced benders memorize a few key multipliers (45-degree is especially common), but using a calculator eliminates guessing.
Offset bends avoid ducts, pipes, and structural members. Kick bends get around floor joists or roof rafters. Saddle bends thread conduit over pipes or under equipment mounting. All of these require calculating travel and shrink; none are eyeballed accurately. An electrician who can bend accurate conduit on the first try is worth a premium; one who bends conduit three times wastes time and material.
Code References
- NEC Article 344 (Rigid) and Article 342 (Intermediate): Bending radius and bend-limit rules (no more than four 90° bends or equivalent in one run between pull points)
- NEC Article 358 (EMT): Similar bending rules for metal tubing
- Trade Standards: Bend calculations follow NECA (National Electrical Contractors Association) standards and are published in pipe-bending reference manuals
Frequently Asked Questions
What’s the minimum bending radius for different conduit types?
- EMT (1/2”–1”): 4× the trade diameter (e.g., 1/2” EMT = 2” bending radius minimum)
- Rigid and Intermediate (1/2”–1”): same as EMT; larger sizes have different minimums
- Check the specific NEC article for the conduit type and size you’re using. Overbending causes kinking and reduces wire-pulling area.
If I’m making four 45-degree bends in one run, am I at the NEC limit?
Four 90-degree bends equal one “full rotation” (360 degrees). Four 45-degree bends = 180 degrees, or half a rotation. You’re under the limit. However, check your local jurisdiction; some require a pull box after three bends regardless of total degrees.
Can I use different bend angles in the same run?
Yes. A 45-degree offset followed by a 30-degree kick is legal and sometimes necessary. Calculate each bend separately and deduct all shrinkage from your conduit length. However, mixing angles makes bending more complex; stick to one angle per job when possible.
How do I mark conduit for a three-bend saddle?
Use a saddle-bend deduct table specific to your angle and obstacle height. Mark the centerline (center of the middle bend), then measure the deduct value upstream and downstream to locate the first and third bends. The middle bend is the critical one; get it accurate and the other two follow. Most benders use pre-printed deduct charts or rely on memorized values for common heights.
What if my conduit is slightly bent or kinked before I start bending?
Replace it. Bending already-kinked conduit will kink worse and reduce the internal area, making it impossible to pull wire. Never bend damaged conduit; it’s not worth the risk of wire damage or failed inspection. Buy fresh conduit.