Key Takeaways
- Three numbers cover most bending math: deduct for stub-ups, multiplier for mark spacing on offsets, and shrink to keep the conduit from coming up short.
- Standard EMT deducts are 5" (1/2"), 6" (3/4"), 8" (1"), and 11" (1-1/4"). These values are stamped on every hand bender.
- The three offset angles electricians use most are 30 degrees (2x multiplier), 45 degrees (1.41x), and 60 degrees (1.15x).
- Use the free online calculators or the Conduit Bending app to skip the arithmetic and get accurate marks for any bend.
Whether you're an apprentice making your first stub-up or a journeyman running parallel offsets, conduit bending comes down to knowing the right numbers and applying them correctly. This guide puts all the reference charts, formulas, and calculator links in one place so you can find what you need without digging through multiple sources.
For a complete walkthrough of every bend type with step-by-step instructions, see How to Bend Conduit. This page focuses on the numbers: deduct values, multipliers, shrink constants, and gain formulas.
Getting Started with Conduit Bending
Conduit bending requires a hand bender matched to your conduit size, a tape measure, a marker, and a few memorized values. The bender does the physical work. The math tells you where to place your marks.
There are three categories of bends you need to know:
- Stub-ups (90-degree bends): The conduit goes from horizontal to vertical. You subtract the deduct from your stub height to find where to mark. See the 90-degree bend guide.
- Offsets: Two bends that move the conduit sideways to clear an obstacle. You multiply the offset height by a multiplier to find the distance between bend marks. See the offset bend guide.
- Saddle bends: Three or four bends that go over an obstruction and return to the original plane. See the 3-point saddle and 4-point saddle guides.
Every other bend type (back-to-back 90s, kicked 90s, rolling offsets, corner bends) is a variation of these three. The formulas below apply to all of them. For a deeper look at the math behind each formula, see Conduit Bending Formulas and Deduct Charts.
Essential Bending Formulas
Three formulas handle the vast majority of bending calculations. Memorize these and you can work through any standard bend on the job site.
Stub-Up Formula (90-Degree Bends)
Mark distance = Stub height - Deduct
The deduct accounts for the arc of the bend. Measure from the end of the conduit to place your mark at the bender arrow. The 90-degree bend calculator does this instantly for any conduit size.
Offset Formula
Distance between marks = Offset height x Multiplier
The multiplier comes from the bend angle. Most electricians default to 30 degrees (multiplier = 2) because the math is easy. The offset bend calculator handles any angle.
Shrink Formula
Shrink = Offset height x Shrink constant
Add the shrink amount to your first mark distance from the conduit end. Forgetting shrink is the most common mistake apprentices make. The shrink calculator computes it for you.
Quick Reference Charts
Deduct/Take-Up Values by Conduit Size
| EMT Size | Deduct | Bend Radius | Min. Stub |
|---|---|---|---|
| 1/2" | 5" | 4" | 5" |
| 3/4" | 6" | 4-1/2" | 6" |
| 1" | 8" | 5-3/4" | 8" |
| 1-1/4" | 11" | 7-1/4" | 11" |
These values are consistent across all major hand bender brands (Ideal, Klein, Gardner Bender, Greenlee). Mechanical and hydraulic benders for 1-1/2" and above use different shoes with different radii. Always verify against the documentation for your specific bender. The Gain and Deduct Calculator covers all conduit types and sizes.
Offset Multipliers & Shrink Constants
| Bend Angle | Multiplier | Shrink per Inch | Shrink Constant |
|---|---|---|---|
| 10° | 5.76 | 1/16" | 0.0625 |
| 15° | 3.86 | 1/8" | 0.132 |
| 22.5° | 2.61 | 3/16" | 0.199 |
| 30° | 2 | 1/4" | 0.25 |
| 45° | 1.41 | 3/8" | 0.414 |
| 60° | 1.15 | 1/2" | 0.577 |
The multiplier is the cosecant of the bend angle (1 / sin(angle)). You don't need to know that on the job, just the three values for 30, 45, and 60 degrees. For a full breakdown of how these numbers work, see the Bending Multiplier Chart. The Bend Multiplier Calculator computes the multiplier, shrink, and mark spacing for any angle.
Gain Values for Cut Length
Gain is the conduit you save when bending a 90 instead of connecting two straight pieces with a fitting. Subtract the gain from the sum of both legs to find the cut length.
| EMT Size | Deduct | Bend Radius | Gain |
|---|---|---|---|
| 1/2" | 5" | 4" | 3-3/4" |
| 3/4" | 6" | 4-1/2" | 4-7/8" |
| 1" | 8" | 5-3/4" | 6-15/16" |
| 1-1/4" | 11" | 7-1/4" | 10-5/8" |
The gain formula is: Gain = (2 x Deduct) - (Radius x 1.5708). The Gain and Deduct Calculator and the Cut Length Calculator handle this for EMT, IMC, and rigid.
Free Online Calculators
Every formula on this page has a matching calculator on conduitbending.com. Punch in your measurements and get results in feet-inches-fractions, the format you actually mark on conduit.
- Offset Bend Calculator - mark spacing and shrink for any offset angle
- Rolling Offset Calculator - 3D offsets with rise and roll
- 3-Point Saddle Calculator - center and outer mark placement
- 4-Point Saddle Calculator - double-offset saddle marks
- 90-Degree Bend Calculator - stub-up mark from deduct
- Back-to-Back 90 Calculator - two 90s on one stick
- Kicked 90 Calculator - 90 with a built-in offset
- Parallel Offset Calculator - mark spacing for multiple conduits side by side
- Conduit Shrink Calculator - shrink compensation for any offset
- Bend Multiplier Calculator - multiplier and shrink for any angle
- Conduit Fill Calculator - NEC fill percentage and wire count
- Degrees per Inch Calculator - segment bending for large radius bends
- Gain and Deduct Calculator - gain values for cut length calculations
- Corner Bend Calculator - bends around corners and obstructions
- Cut Length Calculator - total conduit needed for a run
- Wire Pull Calculator - pulling tension estimates
The Conduit Bending App
Charts and online calculators work well at a desk. On the job site, you need something faster. The Conduit Bending app for iOS puts all 16 calculators in your pocket and adds features that a chart can't match.
| Feature | Charts / Mental Math | Online Calculators | Conduit Bending App |
|---|---|---|---|
| Standard angles | Yes | Yes | Yes |
| Any custom angle | Requires trig | Yes | Yes |
| EMT, IMC, Rigid | Separate charts | Yes | Yes (1/2" to 4") |
| Parallel bends | Complex math | Yes | Yes (auto spacing) |
| Fraction output | Manual conversion | Yes | Yes |
| Bender library | No | No | Yes (all brands) |
| Works offline | Yes | No | Yes |
The app is free to download. See all features or get it on the App Store.
Bending Guides & Tutorials
Each guide below walks through a specific bend type with formulas, worked examples, and tips for getting it right the first time.
- How to Bend Conduit - complete beginner's guide covering every bend type
- 90-Degree Bend and Back-to-Back 90s - deduct values, stub-up calculations, worked examples
- Offset Bend Guide - offset formulas, multiplier tables, worked examples
- Rolling Offset Guide - 3D trigonometry, formulas, field examples
- 3-Point Saddle Bend Guide - formulas, shrink values, step-by-step instructions
- 4-Point Saddle Bend Guide - formulas, instructions, field tips
- Bending Formulas and Deduct Charts - detailed formula reference with worked examples
- Bending Multiplier Chart - offset multiplier table with shrink constants
- Conduit Fill Chart - NEC Chapter 9 wire counts by conduit size
- EMT vs Rigid vs IMC Conduit - compare conduit types, specs, NEC use cases
- Conduit Bending Tools and Quick Reference Charts - tools, app comparison, calculator directory
NEC Bending Requirements
Two NEC (NFPA 70) rules affect every conduit run:
- 360-degree rule (NEC 358.26): Total bending degrees between pull points cannot exceed 360 degrees. That's four 90s maximum, or any combination adding up to 360. Offsets count toward the total. Exceeding 360 degrees creates excessive friction during wire pulls that can damage conductor insulation. The EC&M code Q&A explains this restriction.
- Minimum bending radius (NEC Chapter 9, Table 2): Each conduit type and size has a minimum bend radius. Standard hand benders are manufactured to meet these minimums, but field bending with a hickey or Chicago bender requires verification.
Frequently Asked Questions
What do I need to start bending conduit?
You need a hand conduit bender sized for your conduit (1/2-inch EMT for beginners), a tape measure, a marker, and a level. A hand bender for 1/2-inch EMT costs around $30-$50 and comes with deduct and multiplier values stamped on the frame. Start with scrap EMT to practice before working on actual runs.
Does the deduct value apply to bends other than 90 degrees?
No. Deduct (also called take-up) is specifically for 90-degree stub-up bends. It tells you how far from the end of the conduit to place your mark so the stub comes out at the right height. Offset bends use multipliers and shrink constants instead of deduct values. Saddle bends use a combination of multipliers for mark spacing.
What is the difference between EMT, IMC, and rigid conduit?
EMT (Electrical Metallic Tubing) is the thinnest and lightest, bent with a hand bender, and used in most commercial and residential interior work. IMC (Intermediate Metal Conduit) has a thicker wall than EMT, provides more protection, and is used where conduit needs extra mechanical strength. Rigid (RMC/GRC) is the heaviest, typically requires a mechanical or hydraulic bender for larger sizes, and is used in exposed outdoor runs, hazardous locations, and where maximum protection is needed. See the full comparison at EMT vs Rigid vs IMC.
How many bends can I have in one conduit run?
Per NEC Section 358.26, the total degrees of bends between pull points cannot exceed 360 degrees. That equals four 90-degree bends, or any combination adding up to 360 degrees. Offsets count toward the total (a 30-degree offset = two 30-degree bends = 60 degrees). If your run requires more than 360 degrees, add a pull box or conduit body to reset the count.
Why does my conduit come up short after bending an offset?
You're not accounting for shrink. Every offset bend shortens the overall conduit run because the pipe follows a longer diagonal path through the offset. At 30 degrees, shrink is 1/4 inch per inch of offset height. At 45 degrees, it's 3/8 inch per inch. Add the shrink amount to your first bend mark distance from the end to compensate. Use the shrink calculator to get the exact value.
