Junction Box Sizing Calculator

Find minimum junction box length for straight pulls (NEC).

Minimum box length 8

Formula: straight-pull box length = 8 × largest conduit

Step-by-step with your numbers:

1. Values used:

2. Largest conduit size = 1

4. Minimum box length = 8

Did we solve your problem today?

For a straight pull, the junction box length must be at least 8× the largest conduit diameter (NEC).

The math behind it

minimum box length = 8 × largest conduit size. Angle/U-pulls need different dimensions.

1 in conduit → 8 in box.

Angle pull?

Uses 6× the largest conduit plus the sum of others for each wall.