Wire Size Calculator
Determine proper wire gauge based on current, length, and voltage drop.
Back to Home
Inputs
Current (I) in Amperes
Maximum current the wire will carry
One-Way Length in Feet (or Meters)
Distance from source to load (one direction)
System Voltage (V)
12V DC
24V DC
120V AC
240V AC
480V AC
Maximum Voltage Drop (%)
1%
2%
3%
5%
NEC recommends 3% for branch circuits, 5% total
Conductor Material
Copper
Aluminum
Calculate Wire Size
Clear
Results
Voltage Drop Formula:
V
drop
= 2 × I × L × R / 1000
Where R is resistance per 1000 ft, factor of 2 accounts for both conductors
Minimum Wire Size:
Voltage Drop:
Actual Drop Percentage:
AWG Quick Reference (Copper)
AWG
Ampacity
Ω/1000ft
14
15A
2.525
12
20A
1.588
10
30A
0.999
8
50A
0.628
6
65A
0.395
4
85A
0.249
2
115A
0.156
1/0
150A
0.098
Other Tools
Home
Formula Reference
Unit Converter
Graphing Calculator
