Welder Amps to Watts & Duty Cycle Sizing Calculator
Home garage workshops, fabrication shop electrical installation. Calculates primary input power in Watts and sizes circuit conductors using NEC 630 duty-cycle derating multipliers for MIG, TIG, and Stick welders.
Step-by-Step Derivation ▼ Show Steps
Calculations adhere to standard electrical engineering physics and National Electrical Code (NFPA 70) regulations.
Engineering Principles & Calculations
This calculator uses the exact mathematical relationships between Welder Output Amps (e.g. 140A, 200A, 250A), Rated Input Voltage (120V / 240V), Duty Cycle % (e.g. 30%, 60%, 100%) to determine Primary Input Amps, Rated Input Kilowatts, Allowed Conductor Size (NEC 630.11), Recommended Breaker. In practical installations, factors such as ambient raceway temperature, harmonic distortion, duty cycle continuous operation, and conductor impedance must be accounted for by a certified electrician.
Calculates primary input power in Watts and sizes circuit conductors using NEC 630 duty-cycle derating multipliers for MIG, TIG, and Stick welders.
Typical Application & Industry Guidelines
Home garage workshops, fabrication shop electrical installation.
Welder Amps to Watts & Duty Cycle Sizing Calculator Benchmark Lookup Table
| Welder Output | Primary Input Amps (240V) | Duty Cycle % | Effective Wire Amps | Min Wire Gauge |
|---|---|---|---|---|
| 140A MIG Welder | 20.0 Amps | 30% Duty Cycle | 11.0 Amps | #14 AWG Copper |
| 180A MIG Welder | 28.0 Amps | 30% Duty Cycle | 15.3 Amps | #12 AWG Copper |
| 210A Multi-Process | 36.0 Amps | 30% Duty Cycle | 19.7 Amps | #12 AWG Copper |
| 250A Industrial MIG | 48.0 Amps | 40% Duty Cycle | 30.4 Amps | #10 AWG Copper |
| 300A Heavy Fab TIG | 60.0 Amps | 60% Duty Cycle | 46.5 Amps | #8 AWG Copper |