Wire Gauge Calculator | AWG Wire Size & Voltage Drop

Find the correct AWG wire gauge size for your current load and run length

Calculate voltage drop percentage and check NEC compliance for copper and...

When Should You Use This Calculator?

Getting a quick AWG recommendation from voltage, current, and run length
Running safety-oriented review with NEC-style 3% and 5% voltage-drop targets
Comparing copper vs aluminum and environment assumptions
Using advanced phase/installation controls for engineering scenarios
Validating voltage drop and power-loss impacts before wiring decisions

How to Use This Calculator

Enter the load current in amps, the run length, and the system voltage.
Select conductor material (copper or aluminum).
Expand NEC Compliance to set insulation temperature rating and installation method.
Review the recommended AWG wire size, expected voltage drop, and ampacity against NEC limits.

Key Features:

AWG sizing from voltage drop and ampacity
Branch (3%) and feeder (5%) presets; copper/aluminum
NEC temperature correction and conduit ratings
Copy results and export (JSON for guests; PDF/CSV when signed in)

Frequently Asked Questions

How do I choose the right wire gauge?

Start in Simple mode with voltage, current, and run length. Heavier loads and longer distances need thicker wire (lower AWG number). Use Safety Review/Advanced modes for installation and environment assumptions.

What is acceptable voltage drop?

A common NEC guideline is 3% for branch circuits and 5% combined for feeder + branch. Safety Review mode includes quick 3%/5% targets so you can test both scenarios quickly.

What AWG wire do I need for a 20-amp circuit?

A 20-amp circuit requires a minimum of 12 AWG copper wire (NEC 310.15). For long runs where voltage drop is a concern, you may need to upsize to 10 AWG. Enter your specific amperage and run length in this calculator to confirm the correct size.

Does conductor material (copper vs aluminum) affect wire sizing?

Yes. Aluminum wire has about 61% the conductivity of copper, so it requires a larger AWG for the same current capacity. Aluminum is commonly used for service entrance and large feeder circuits. Select your conductor material in Advanced mode for accurate sizing.

What size wire do I need for a 50-amp circuit?

A 50-amp circuit typically needs 6 AWG copper or 4 AWG aluminum for a standard run, based on the NEC 60°C/75°C ampacity tables. Long runs can require upsizing to keep voltage drop under 3%. Enter 50 amps with your actual run length and conductor material above to confirm the correct gauge for your installation.

Can I export my Wire Gauge Calculator calculations?

Yes. In guest mode you can export your calculations to JSON. Signing in adds PDF and CSV export. Click the export button to download your results — useful for record-keeping, sharing, or importing into other tools.

Does this calculator save my history?

Yes. Your calculation history is saved automatically. As a guest you can keep up to 50 calculations per workspace on your device. Sign in for free to keep up to 100 per workspace and access them from any device.

Is this calculator free to use?

Yes. The Wire Gauge Calculator is free to use with no sign-up required. A free account adds more calculation history, multiple workspaces, and access to your saved data from any device.

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