Quick answer
Amps to watts: P = V × A. 1 amp at 120V = 120 watts; 1 amp at 240V = 240 watts; a 20A/120V circuit = 2,400W. Full conversion tables below.
Amps to Watts Calculator
Convert amperage to wattage instantly. Enter amps and volts to calculate watts for solar panels, generators, and electrical systems.
Formula
Amps to Watts Conversion Table
| Amps (A) | 120V | 240V |
|---|---|---|
| 5A | 600W | 1,200W |
| 10A | 1,200W | 2,400W |
| 15A | 1,800W | 3,600W |
| 20A | 2,400W | 4,800W |
| 30A | 3,600W | 7,200W |
| 50A | 6,000W | 12,000W |
| 100A | 12,000W | 24,000W |
Common Solar & Generator Applications
- Calculate total wattage for solar panel arrays
- Size generators for specific appliance loads
- Determine inverter capacity requirements
- Plan battery bank discharge rates
- Size charge controllers for solar systems
How do I convert amps to watts?
Multiply amps by volts: Watts = Amps x Volts. For example, 20A at 120V = 2,400W.
How many watts is 30 amps at 240V?
30 amps x 240 volts = 7,200 watts. This is common for RV shore power and generator transfer switches.
How many amps is a 7,200W generator at 240V?
7,200W / 240V = 30A. This is standard for a 30A generator inlet box.
NEC Wire Sizing Reference Table
Once you know your amp load, you need the correct wire size. The National Electrical Code (NEC) Table 310.16 specifies ampacity ratings for copper and aluminum conductors. Always size wire based on the ampacity at the temperature rating of your terminals (typically 75°C for most equipment).
| AWG Size | Copper Ampacity (60°C) | Copper Ampacity (75°C) | Copper Ampacity (90°C) | Typical Breaker |
|---|---|---|---|---|
| 14 AWG | 15A | 20A | 25A | 15A |
| 12 AWG | 20A | 25A | 30A | 20A |
| 10 AWG | 30A | 35A | 40A | 30A |
| 8 AWG | 40A | 50A | 55A | 40A |
| 6 AWG | 55A | 65A | 75A | 50-60A |
| 4 AWG | 70A | 85A | 95A | 70A |
| 2 AWG | 95A | 115A | 130A | 100A |
| 1/0 AWG | 125A | 150A | 170A | 125A |
| 2/0 AWG | 145A | 175A | 195A | 150A |
| 4/0 AWG | 195A | 230A | 260A | 200A |
Note: Values based on NEC Table 310.16 for copper conductors. Apply NEC 310.15(B) adjustment factors for ambient temperature and conduit fill. Always consult NEC and local codes for final wire sizing.
Breaker Sizing Guide
Circuit breakers protect wire from overcurrent. The general rule is: Breaker size = 125% of continuous load (NEC 210.20(A)). For non-continuous loads, the breaker can be sized at 100% of the load.
| Load Type | Calculation | Example |
|---|---|---|
| Continuous (3+ hrs) | Load × 1.25 | 20A load → 25A breaker |
| Non-continuous | Load × 1.0 | 20A load → 20A breaker |
| Motor (NEC 430.52) | FLC × 2.5 (inverse time) | 10A motor → 25A breaker |
| PV circuit (NEC 690.8) | Isc × 1.56 | 10A Isc → 15A breaker |
Recommended Wire & Breaker Products
Need wire sizing for a specific application? Check our 1/0 AWG wire guide or Amps to kW Calculator for more calculations.
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