NEC Code Compliance calculator

Pull Box Sizing Calculator

A straight pull with a 4 in raceway screens at 32 in minimum; angle rows of 4 in + 2 in and 3 in + 2 in screen as a 26 in x 20 in box footprint for the checked axes. This pull box sizing calculator is a planning-level NEC 314.28 screen for pull and junction boxes with conductors 4 AWG and larger. It checks straight pulls at 8 times the largest raceway trade size and checks angle and U-pulls from the governing raceway row on each wall. It is intentionally narrower than a full layout review, so results should be verified against the actual raceway arrangement and the adopted NEC.

Updated June 21, 2026

A straight pull with a 4 in raceway screens at 32 in minimum. An angle pull with a 4 in + 2 in governing row screens at 26 in from that wall.

Straight pull: 8 × largest raceway | Angle or U-pull: 6 × largest raceway in the governing row + the remaining raceway sizes on that same row.

Choose straight, angle, or U-pull below and enter the governing raceway row for the wall you are checking

Calculator Inputs

Calculation Results

Enter values above to see calculation results

Calculation history

Example Calculations

Angle pull with 4 in + 2 in on one wall and 3 in + 2 in on the adjacent wall

Wall A screens at 26 inches and Wall B screens at 20 inches, so the box footprint screens at 26 in x 20 in for the checked axes.

Inputs

Pull Type: Angle pull
Wall A Raceways: 4,2
Wall B Raceways: 3,2

Straight pull with a 3 in raceway and no splices

A single straight-pull axis with a 3 in raceway screens at 24 inches before enclosure layout and access checks.

Inputs

Pull Type: Straight pull
Straight Raceway Trade Size: 3
Splice Included: false

How to Use

What this pull box sizing calculator actually checks

This page is not a full pull-box layout engine. It is a clear formula screen for the most common NEC 314.28 checks that electricians and designers reach for first:

Straight pull: 8 x the trade size of the largest raceway on the pull axis being checked.
Angle pull: 6 x the largest raceway in the governing row on a wall, plus the sum of the remaining raceway sizes in that same row.
U-pull: the same governing-row rule, plus the spacing check for the raceways enclosing the same conductors.

What “governing row” means

For angle and U-pulls, you do not add every raceway on the wall into one giant number unless they are actually on the same row being evaluated. The row that produces the largest required dimension is the governing row. If a wall has more than one row of raceways, each row should be checked separately and the largest result should control.

Straight-pull rule

Minimum dimension in the pull direction = 8 x largest raceway trade size

Largest raceway	Minimum straight-pull dimension
2 in	16 in
3 in	24 in
4 in	32 in
6 in	48 in

Angle-pull rule

Minimum distance from a checked wall to the opposite wall = 6 x the largest raceway in the governing row + the sum of the remaining raceway sizes in that same row

If Wall A has a governing row of 4 in and 2 in, the minimum dimension from Wall A to the opposite wall is:

6 x 4 + 2 = 26 in

If the adjacent Wall B has a governing row of 3 in and 2 in, the minimum dimension from Wall B to the opposite wall is:

6 x 3 + 2 = 20 in

That produces a minimum box footprint of 26 in x 20 in for the two checked axes.

U-pull rule

U-pulls use the same governing-row calculation for the distance to the opposite wall. In addition, the raceways enclosing the same conductors need a spacing check based on the larger of the paired raceways. This page reports both values so the user can review the wall-to-opposite-wall dimension and the paired-raceway spacing together.

Scope limits that matter

This page is for conductors 4 AWG and larger.
It is a trade-size screen, not a three-dimensional constructability review.
It does not model every exception, every back-entry arrangement, or every removable-cover case.
It assumes the user already knows which row is governing on each checked wall.

When to use box-fill instead

If the conductors are 6 AWG and smaller, the usual box-size conversation shifts to smaller-box box-fill rules rather than the pull-box bending-space rules screened here. This is why this page stays focused on large-conductor pull and junction boxes only.

How to use this page with related tools

Use the conduit fill calculator for raceway occupancy, the wire size calculator for conductor sizing, and the voltage drop calculator when the run length itself is part of the design question.

After the dimension screen, use the Pull Box Sizing Chart to record pull type, governing row, raceway entries, splice notes, access direction, and whether the result still needs a field-layout check.

Common Applications

Checking straight-pull dimensions from the largest raceway trade size

Checking angle-pull box width and height from one governing row on each wall

Checking U-pull wall-to-opposite-wall distance and paired-raceway spacing

Cross-checking pull-box dimensions before final layout and field installation

Reviewing large-conductor pull and junction boxes for feeder and service raceways

Teaching the difference between straight-pull and angle/U-pull NEC 314.28 math

Frequently Asked Questions

What is the straight-pull formula for a pull box?

For the axis being checked, the minimum straight-pull dimension is 8 times the trade size of the largest raceway on that pull axis. A 4-inch raceway therefore screens at 32 inches minimum in the pull direction.

How do I calculate an angle pull box with multiple raceways on a wall?

Use the governing row on each checked wall. For each wall, take 6 times the largest raceway in that row and add the trade sizes of the remaining raceways in that same row. If different walls produce different results, the box must satisfy both checked wall dimensions.

Why does this page ask for the governing row instead of every raceway on the wall?

Because angle and U-pull sizing is row-sensitive. If a wall has multiple rows, each row should be checked separately and the largest result governs. Asking for the governing row keeps the page honest instead of pretending that one giant total always represents the code requirement correctly.

Does this page apply to all conductors?

No. This page is for pull and junction boxes with conductors 4 AWG and larger. Smaller-conductor box sizing is usually addressed through box-fill rules rather than this large-conductor bending-space screen.

Does this page replace the final field layout?

No. It is a formula screen. Final design still depends on the actual raceway arrangement, any additional rows, the complete wall layout, conductor type, and the adopted code edition.

What should I record after a pull box sizing result?

Record the pull type, governing row on each wall, largest raceway, remaining raceways in that row, splice or no-splice assumption, access direction, and any field-layout notes. The pull box sizing chart keeps those assumptions attached to the dimension result.

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