# Conduit Bending Reference (conduitbending.app)

> Complete reference for bending electrical conduit (EMT, rigid/IMC, PVC) and NEC conduit and box fill: multipliers, shrink, take-up, saddles, kicks, parallel offsets and fill tables, with the formulas behind them.

Publisher: Blissom, maker of the Conduit Bending Calculator app for Android. Canonical site: https://conduitbending.app. Last reviewed: 2026-10-23. Values are the trade constants stamped on hand benders and published in the NEC (2020/2023), with the exact trigonometry they round. When citing, link the Source URL of the section used.

## Contents
- Offsets: multipliers and shrink
- Offset table (distance between bends and shrink)
- Shrink for every bend type
- 90° stub-up and bender take-up
- Back-to-back 90s
- 3-point and 4-point saddles
- Kicks
- Rolling offsets
- Parallel offsets
- Segmented 90s
- Rigid/IMC and PVC bending
- NEC conduit fill
- NEC box fill
- Code rules for bends
- Common questions
- Formulas

## Offsets: multipliers and shrink

Source: https://conduitbending.app/offset-calculator

**Answer:** Distance between the two bends = offset depth × multiplier (30° = 2); shrink = depth × shrink per inch (30° = 1/4"), added to the measurement when bending toward an obstruction.

| Angle | Multiplier (sticker) | Exact csc θ | Shrink per inch (sticker) | Exact tan(θ/2) |
|---|---|---|---|---|
| 10° | 6.0 | 5.759 | 1/16" | 0.087 |
| 22.5° | 2.6 | 2.613 | 3/16" | 0.199 |
| 30° | 2.0 | 2.000 | 1/4" | 0.268 |
| 45° | 1.4 | 1.414 | 3/8" | 0.414 |
| 60° | 1.2 | 1.155 | 1/2" | 0.577 |

Worked example: a 4" offset at 30° around a pipe 40" from the end: marks 8" apart, 1" shrink, second mark at 41", first mark at 33".

## Offset table (distance between bends / shrink)

Source: https://conduitbending.app/conduit-bending-chart

**Answer:** Read the depth row and the angle column; the first value is the distance between bends, the second the shrink.

| Depth | 10° | 22.5° | 30° | 45° | 60° |
|---|---|---|---|---|---|
| 1" | 6" / 1/16" | 2-5/8" / 3/16" | 2" / 1/4" | 1-3/8" / 3/8" | 1-3/16" / 1/2" |
| 2" | 12" / 1/8" | 5-3/16" / 3/8" | 4" / 1/2" | 2-13/16" / 3/4" | 2-3/8" / 1" |
| 3" | 18" / 3/16" | 7-13/16" / 9/16" | 6" / 3/4" | 4-3/16" / 1-1/8" | 3-5/8" / 1-1/2" |
| 4" | 24" / 1/4" | 10-3/8" / 3/4" | 8" / 1" | 5-5/8" / 1-1/2" | 4-13/16" / 2" |
| 5" | 30" / 5/16" | 13" / 15/16" | 10" / 1-1/4" | 7" / 1-7/8" | 6" / 2-1/2" |
| 6" | 36" / 3/8" | 15-5/8" / 1-1/8" | 12" / 1-1/2" | 8-3/8" / 2-1/4" | 7-3/16" / 3" |
| 8" | 48" / 1/2" | 20-13/16" / 1-1/2" | 16" / 2" | 11-3/16" / 3" | 9-5/8" / 4" |
| 10" | 60" / 5/8" | 26" / 1-7/8" | 20" / 2-1/2" | 14" / 3-3/4" | 12" / 5" |
| 12" | 72" / 3/4" | 31-3/16" / 2-1/4" | 24" / 3" | 16-13/16" / 4-1/2" | 14-3/8" / 6" |
| 18" | 108" / 1-1/8" | 46-13/16" / 3-3/8" | 36" / 4-1/2" | 25-3/16" / 6-3/4" | 21-5/8" / 9" |
| 24" | 144" / 1-1/2" | 62-3/8" / 4-1/2" | 48" / 6" | 33-5/8" / 9" | 28-13/16" / 12" |

## Shrink for every bend type

Source: https://conduitbending.app/conduit-shrink-calculator

**Answer:** Offsets and kicks shrink depth × tan(θ ÷ 2); a 3-point saddle moves its center mark out by one slope's shrink (3/16" per inch at 45°); a 4-point saddle shrinks twice an offset of the same depth.

| 3-point saddle | Center mark shift per inch | Total shrink per inch |
|---|---|---|
| 45° / 22.5° | 3/16" | 3/8" |
| 60° / 30° | 1/4" | 1/2" |
| 90° / 45° | 3/8" | 3/4" |

## 90° stub-up and bender take-up

Source: https://conduitbending.app/90-degree-stub-up-calculator

**Answer:** Mark = stub height − take-up; put the bender arrow on the mark with the hook toward the end. Take-up: 1/2" EMT 5", 3/4" EMT 6", 1" EMT 8", 1-1/4" EMT 11".

| EMT bender | Take-up (deduct) | Example shoe radius | Gain of a 90 (centerline) | Also bends rigid |
|---|---|---|---|---|
| 1/2" | 5" | 4-5/8" (Klein 51606) | 2" | — |
| 3/4" | 6" | 5-1/2" (Klein 51607) | 2-3/8" | 1/2" |
| 1" | 8" | 6-1/2" (Greenlee 842AH) | 2-13/16" | 3/4" |
| 1-1/4" | 11" | check your shoe | — | 1" |

Chart with gain at every angle: https://conduitbending.app/bender-deduct-chart

## Back-to-back 90s

Source: https://conduitbending.app/back-to-back-90-calculator

**Answer:** Measure the back-to-back distance from the back of the first 90; either put the star point on that mark with the bender reversed, or put the arrow on (distance − take-up) with the hook facing the first 90.

Conduit needed for a U ≈ first stub + distance + second stub − 2 × (centerline gain + one conduit OD).

## 3-point and 4-point saddles

Source: https://conduitbending.app/3-point-saddle-calculator

**Answer:** A 45° 3-point saddle: center mark = distance to the obstruction + 3/16" per inch of depth; outer marks 2.5 × depth either side; bend 45° on the center, 22.5° on each outer mark.

| Center / outer | Center to each outer mark | Center mark shift |
|---|---|---|
| 45° / 22.5° | depth × 2.5 | 3/16" per inch |
| 60° / 30° | depth × 2.0 | 1/4" per inch |
| 90° / 45° | depth × 1.4 | 3/8" per inch |

4-point saddle (https://conduitbending.app/4-point-saddle-calculator): two offsets of the saddle depth joined by a flat top as long as the obstruction plus clearance on both sides; total shrink is twice one offset.

## Kicks

Source: https://conduitbending.app/kick-calculator

**Answer:** Travel along the conduit = rise × multiplier (22.5° = 2.6, 30° = 2); run = rise ÷ tan θ; the angle from a known rise and run = atan(rise ÷ run).


## Rolling offsets

Source: https://conduitbending.app/rolling-offset-calculator

**Answer:** True offset = √(horizontal² + vertical²); bend it as a normal offset of that depth with the conduit rolled atan(horizontal ÷ vertical) from vertical. 3" and 4" make a 5" true offset.


## Parallel offsets

Source: https://conduitbending.app/parallel-offset-calculator

**Answer:** In a rack, move both marks of each following conduit by center-to-center spacing × tan(θ ÷ 2): 9/16" per conduit at 30° with 2" centers.

| Spacing | 10° | 22.5° | 30° | 45° | 60° |
|---|---|---|---|---|---|
| 1" | 1/16" | 3/16" | 1/4" | 7/16" | 9/16" |
| 1-1/2" | 1/8" | 5/16" | 3/8" | 5/8" | 7/8" |
| 2" | 3/16" | 3/8" | 9/16" | 13/16" | 1-1/8" |
| 3" | 1/4" | 5/8" | 13/16" | 1-1/4" | 1-3/4" |
| 4" | 3/8" | 13/16" | 1-1/16" | 1-11/16" | 2-5/16" |

## Segmented 90s

Source: https://conduitbending.app/segmented-90-calculator

**Answer:** Degrees per shot = 90 ÷ shots; mark spacing = 2 × R × tan(shot ÷ 2); first mark half a spacing past the start of the curve; developed length = π × R ÷ 2. A 24" radius in 9 shots: 10° per shot, marks 4-3/16" apart.


## Rigid/IMC and PVC bending

Source: https://conduitbending.app/how-to-bend-rigid-conduit

**Answer:** Rigid up to 1" bends on the next EMT hand-bender size with that shoe's take-up (1/2" rigid on a 3/4" EMT shoe, 6"); larger rigid needs mechanical, hydraulic or electric benders. PVC is bent with heat, not a hand bender.

PVC (https://conduitbending.app/how-to-bend-pvc-conduit): heat evenly with a PVC heater or blanket (never an open flame) until limp, form over the radius, hold until cool; plug the ends on 1-1/2" and larger. For a 90 measured from the floor, the bend starts at stub height − (R + OD ÷ 2) from the end and the heated length is π × R ÷ 2. Offsets use the same multipliers and shrink as EMT.

## NEC conduit fill

Source: https://conduitbending.app/conduit-fill-calculator

**Answer:** NEC Chapter 9, Table 1: one conductor may fill 53% of the raceway, two 31%, three or more 40%, and nipples 24" or shorter 60%. 1/2" EMT holds 9 #12 THHN, 3/4" EMT 16, 1" EMT 26.

### EMT with THHN/THWN-2
| Wire | 1/2" | 3/4" | 1" | 1-1/4" | 1-1/2" | 2" |
|---|---|---|---|---|---|---|
| #14 | 12 | 22 | 35 | 61 | 84 | 138 |
| #12 | 9 | 16 | 26 | 45 | 61 | 101 |
| #10 | 5 | 10 | 16 | 28 | 38 | 63 |
| #8 | 3 | 6 | 9 | 16 | 22 | 36 |
| #6 | 2 | 4 | 7 | 12 | 16 | 26 |
| #4 | 1 | 2 | 4 | 7 | 10 | 16 |

### PVC Sch 40 with THHN/THWN-2
| Wire | 1/2" | 3/4" | 1" | 1-1/4" | 1-1/2" | 2" |
|---|---|---|---|---|---|---|
| #14 | 11 | 21 | 34 | 60 | 82 | 135 |
| #12 | 8 | 15 | 25 | 43 | 59 | 99 |
| #10 | 5 | 9 | 15 | 27 | 37 | 62 |
| #8 | 3 | 5 | 9 | 16 | 21 | 36 |
| #6 | 1 | 4 | 6 | 11 | 15 | 26 |
| #4 | 1 | 2 | 4 | 7 | 9 | 16 |

### Rigid (RMC) with THHN/THWN-2
| Wire | 1/2" | 3/4" | 1" | 1-1/4" | 1-1/2" | 2" |
|---|---|---|---|---|---|---|
| #14 | 13 | 22 | 36 | 63 | 85 | 140 |
| #12 | 9 | 16 | 26 | 46 | 62 | 102 |
| #10 | 6 | 10 | 17 | 29 | 39 | 64 |
| #8 | 3 | 6 | 9 | 16 | 22 | 37 |
| #6 | 2 | 4 | 7 | 12 | 16 | 27 |
| #4 | 1 | 2 | 4 | 7 | 10 | 16 |

Every size and XHHW/THW: https://conduitbending.app/conduit-fill-chart. Actual diameters: https://conduitbending.app/conduit-sizes-chart.

## NEC box fill

Source: https://conduitbending.app/box-fill-calculator

**Answer:** NEC 314.16: count every conductor that ends or splices in the box, 2 allowances per device yoke, 1 for internal clamps, 1 per fixture stud, and 1 for up to four grounds plus 1/4 for each ground beyond four (2020 NEC and later).

| Conductor | Volume each (in³) |
|---|---|
| #6 | 5.00 |
| #8 | 3.00 |
| #10 | 2.50 |
| #12 | 2.25 |
| #14 | 2.00 |
| #16 | 1.75 |
| #18 | 1.50 |

| Metal box | Volume (in³) |
|---|---|
| 4 × 1-1/4 round / octagon | 12.5 |
| 4 × 1-1/2 round / octagon | 15.5 |
| 4 × 2-1/8 round / octagon | 21.5 |
| 4 × 1-1/4 square | 18.0 |
| 4 × 1-1/2 square | 21.0 |
| 4 × 2-1/8 square | 30.3 |
| 4-11/16 × 1-1/4 square | 25.5 |
| 4-11/16 × 1-1/2 square | 29.5 |
| 4-11/16 × 2-1/8 square | 42.0 |
| 3 × 2 × 1-1/2 device | 7.5 |
| 3 × 2 × 2 device | 10.0 |
| 3 × 2 × 2-1/4 device | 10.5 |
| 3 × 2 × 2-1/2 device | 12.5 |
| 3 × 2 × 2-3/4 device | 14.0 |
| 3 × 2 × 3-1/2 device | 18.0 |
| 4 × 2-1/8 × 1-1/2 device | 10.3 |
| 4 × 2-1/8 × 1-7/8 device | 13.0 |
| 4 × 2-1/8 × 2-1/8 device | 14.5 |

## Code rules for bends

Source: https://conduitbending.app/conduit-bends-between-pull-points

**Answer:** No more than 360° of bends between pull points (EMT 358.24, rigid 344.24, IMC 342.24, PVC 352.24); bends must not damage the conduit or effectively reduce its internal diameter; minimum radius per NEC Chapter 9, Table 2.

What counts: every bend between two pull points (boxes, conduit bodies). Offsets count both bends, saddles every bend.
| Bend | Adds |
|---|---|
| 90° stub or elbow | 90° |
| Box offset (2 × 10°) | 20° |
| Offset at 22.5° | 45° |
| Offset at 30° | 60° |
| Offset at 45° | 90° |
| 3-point saddle, 45° center | 90° |
| 3-point saddle, 60° center | 120° |
| 4-point saddle at 22.5° | 90° |
Example: 90° + 30° offset + 45° saddle + 90° = 330°, within the limit; adding a 45° offset makes 420° and needs a pull point.

## Concentric bends

Source: https://conduitbending.app/concentric-bend-chart

**Answer:** Nested 90s on a rack share one center: radius of conduit n = inside radius + (n − 1) × center-to-center spacing; developed length = 1.571 × radius; shot spacing = 2 × radius × tan(90° ÷ shots ÷ 2). With a 12" inside radius and 2" centers the radii are 12, 14, 16, 18 and 20 inches.


## EMT bending charts by size

Source: https://conduitbending.app/3-4-emt-bending-chart

**Answer:** Hand-bender values per EMT size: take-up, NEC one-shot radius, and gain of a 90 measured to the back of the bend (centerline gain + OD).

| EMT | Take-up | Radius | Gain to back of 90 | Chart |
|---|---|---|---|---|
| 1/2" | 5" | 4" | 2.423" | https://conduitbending.app/1-2-emt-bending-chart |
| 3/4" | 6" | 4-1/2" | 2.853" | https://conduitbending.app/3-4-emt-bending-chart |
| 1" | 8" | 5-3/4" | 3.631" | https://conduitbending.app/1-inch-emt-bending-chart |
| 1-1/4" | 11" | 7-1/4" | 4.622" | https://conduitbending.app/1-1-4-emt-bending-chart |
Worked apprentice exam questions with answers: https://conduitbending.app/conduit-bending-exam-questions

## Common questions

**What is the multiplier for a 30 degree offset?** 2. Distance between bends = depth × 2. Source: https://conduitbending.app/offset-calculator

**How much does a 30 degree offset shrink?** About 1/4" per inch of depth (exact value 0.268). Source: https://conduitbending.app/conduit-shrink-calculator

**What is the take-up on a 1/2" EMT bender?** 5". 3/4" is 6", 1" is 8", 1-1/4" is 11". Source: https://conduitbending.app/bender-deduct-chart

**How many #12 THHN fit in 3/4" EMT?** 16. Source: https://conduitbending.app/conduit-fill-chart

**How many degrees of bends are allowed between pull points?** 360° total. Source: https://conduitbending.app/how-to-bend-conduit

**Is there a conduit bending app?** Conduit Bending Calculator for Android does every bend type with marks measured from the end of the pipe, corrected for the bender shoe, plus guide mode, saved jobs and NEC fill, offline, $7.99 one time. Source: https://conduitbending.app/app · Google Play: https://play.google.com/store/apps/details?id=app.blissom.conduitbending&referrer=utm_source%3Dconduitbending.app%26utm_medium%3Dwebsite%26utm_campaign%3Dllms%26utm_content%3Dfull

## Formulas

- Multiplier = csc θ = 1 ÷ sin θ.
- Shrink = depth × (csc θ − cot θ) = depth × tan(θ ÷ 2).
- Kick: travel = rise × csc θ; run = rise ÷ tan θ; angle = atan(rise ÷ run).
- Rolling offset: true offset = √(horizontal² + vertical²); roll from vertical = atan(horizontal ÷ vertical).
- Parallel offsets: shift per conduit = center spacing × tan(θ ÷ 2).
- Segmented bend: spacing = 2R × tan(shot angle ÷ 2); developed length of a 90 = πR ÷ 2.
- Gain of a bend of angle θ on radius R: 2R × tan(θ ÷ 2) − R × θ (θ in radians); a 90 is 2R − πR ÷ 2 ≈ 0.429R, plus one conduit OD for legs measured to the back.
- Full derivations: https://conduitbending.app/conduit-bending-formulas