Wire Size Calculator
Determine the correct wire gauge for your electrical project
Wire Size Calculator
Determine the correct wire gauge (AWG) for your electrical project based on current, voltage, distance, and acceptable voltage drop. Supports copper and aluminum conductors for DC, single-phase AC, and three-phase AC circuits.
🧵 Wire Size Calculator
📊 Results
Wire Gauge Comparison
| AWG | V Drop | Drop % | Max Amps | Status |
|---|
Calculation Details
📚 Understanding Wire Sizing
What is AWG?
American Wire Gauge (AWG) is the standard system for measuring wire diameter in North America. Smaller AWG numbers indicate larger wire diameters. Each decrease of 3 AWG numbers doubles the cross-sectional area and ampacity of the wire.
Why Wire Size Matters
Undersized wires cause excessive voltage drop, energy waste, and overheating — creating fire hazards. Oversized wires waste money. The right wire size ensures safety, efficiency, and code compliance.
NEC Guidelines
The National Electrical Code (NEC) recommends maximum 3% voltage drop for branch circuits and 5% total (feeder + branch). Wire must also meet ampacity requirements based on insulation type and ambient temperature.
Wire Sizing Factors
- Current (Ampacity): The wire must safely carry the expected load current without exceeding its temperature rating.
- Voltage Drop: Longer runs require larger wire to keep voltage drop within acceptable limits.
- Wire Material: Copper has ~61% better conductivity than aluminum, allowing smaller gauges for the same load.
- Ambient Temperature: Higher temperatures reduce a wire's ampacity, potentially requiring larger wire.
- Conduit Fill: Multiple wires in a conduit generate more heat, requiring derating of ampacity.
- Circuit Type: Three-phase circuits have a √3 factor difference in voltage drop calculations vs single-phase.
Voltage Drop Formulas
Single-phase & DC (round-trip)
Three-phase circuits
AWG Quick Reference
| AWG | Diameter (mm) | Copper Amps (60°C) | Aluminum Amps (60°C) | Typical Use |
|---|---|---|---|---|
| 14 | 1.63 | 15 A | — | Lighting circuits |
| 12 | 2.05 | 20 A | 15 A | Outlets, general circuits |
| 10 | 2.59 | 30 A | 25 A | Dryers, water heaters |
| 8 | 3.26 | 40 A | 30 A | Ranges, large AC |
| 6 | 4.11 | 55 A | 40 A | Subpanels, large loads |
| 4 | 5.19 | 70 A | 55 A | Service entrance |
| 2 | 6.54 | 95 A | 75 A | Service entrance, feeders |
| 1/0 | 8.25 | 125 A | 100 A | Main service |