Electrical calculator
Wire Gauge Calculator
Estimate appropriate wire gauge based on amperage and length.
About the wire gauge calculator
The wire gauge calculator recommends the appropriate AWG wire size based on amperage, length, and conductor material (copper or aluminum).
How to use this calculator
- 1
Enter amperage
Enter the circuit's maximum current draw in amps.
- 2
Enter length
Enter the one-way wire run length in feet.
- 3
Choose material
Select copper or aluminum conductor.
How the calculation works
Uses NEC guidelines: longer runs need larger wire to prevent voltage drop.
Example: 30A over 50 ft copper: use 10 AWG.
Safety first
These calculators provide estimates based on standard formulas and NEC guidelines. Always verify results with a licensed electrician before making installations. Electrical work can be dangerous — never work on live circuits, and always follow local building codes and regulations.
Understanding electrical units
Voltage (V) is electrical pressure, current (A) is flow rate, resistance (Ω) opposes flow, and power (W) is the rate of energy use. Ohm's law (V = I × R) relates the first three, while power formulas (P = VI, P = I²R) connect all four. Understanding these relationships is key to safe electrical design.
Important limitations
This tool provides a mathematical estimate based only on the values entered. It does not account for regulations, taxes, lender fees, market conditions, or individual circumstances. Results are for planning purposes only — consult a qualified professional for regulated, medical, financial, or construction decisions.
Frequently asked questions about wire gauge calculator
How accurate is the wire gauge calculator?+
The calculation follows the displayed formula and retains full numeric precision before formatting the result.
Can I use the result professionally?+
Use it as a planning estimate. Confirm regulated, medical, financial, or construction decisions with a qualified professional.