How do I use the Subpanel Sizing & Feeder Wire Calculator?

Enter your specific project or financial parameters into the input fields above. The engine recalculates outputs dynamically in real time and updates visual charts and summary metrics.

Can I export and share these results?

Yes, you can generate shareable state links, export clean CSV spreadsheets, or print high-resolution executive reports with a single click.

Is this calculator free to use?

Yes, all calculation engines on ToolsVault are 100% free with no account registration or paywall required.

NEC Article 215 & 225 Feeder Sizing

Electrical Subpanel Feeder Sizer

Size detached garage, workshop, or basement subpanels. Calculate feeder breaker amps, copper vs aluminum wire size, conduit diameter, and 4-wire grounding requirements.

Subpanel Load & Distance

Target Subpanel Amperage

Conductor Metal

Run Distance (Feet)

Installation Location

Conduit Type

Code Wire Specifications

Feeder Hot Wires 1 AWG AL 2 Hots + 1 Neutral

Equipment Ground 6 AWG AL 4-wire system

Main Feeder Breaker 100 Amp 2-Pole 240V

Conduit Size 1-1/2" PVC / EMT

Voltage Drop 1.6% < 3% NEC limit

Est Material Cost $540 Panel + wire + breaker

Grounding & Bonding: Floating Neutral (Remove Green Screw)

Ground Rods Required: None (Shared Main Panel Ground)

Adding Level 2 EV Chargers or Hot Tubs?

A 100A subpanel easily powers a 48A EV charger (60A breaker) and heavy workshop machinery.

Spa Sizer

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