Box Fill Calculator

Determine the minimum required electrical box volume (mL) based on conductor counts, devices, and internal fittings from Table 22.

14 AWG

12 AWG

10 AWG

8 AWG

6 AWG

Devices (Switches/Outlets)

Internal Cable Clamps

Wire Connectors (Marrettes)

Support Fittings (Studs/Hickeys)

Ground Wire

Includes Bare Grounding

Pro Tip: Ground Wires

No matter how many ground wires enter the box, they collectively only count as one conductor equivalent to the largest ground wire in the box.

Conductor Volume- mL

Device Volume- mL

Marrettes Volume- mL

Clamps / Hardware / Grounds- mL

Drywall / Indoors

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Concrete Block

Masonry 1-gang 2-1/2 depth

Exterior / Wet

FS 1-Gang

Need to verify complex custom scenarios? Consult Henri to cross-reference exact regulatory requirements for your specific installation condition.