Current Calculator (Amperage)
Electrical safety tool to calculate current from Power/Voltage or Resistance/Voltage. Features shock risk warnings and wire gauge (AWG) suggestions.
About
Calculating electrical current (Amperage) is the first step in ensuring the safety of any circuit design. Overloaded wires are a primary cause of electrical fires. This tool calculates current based on standard Ohm's Law and Power Law configurations. Uniquely, it assesses the safety of the resulting current against human physiological thresholds and standard wire capabilities.
Understanding the magnitude of current is critical. While a 5V USB charger pushing 2A is safe to touch, a high-voltage circuit with the same amperage can be lethal. This calculator provides immediate visual feedback (Green/Yellow/Red) based on general safety categories and suggests the minimum American Wire Gauge (AWG) required to handle the load without overheating.
Formulas
Current is calculated using two primary relationships. From Power (P) and Voltage (V):
From Resistance (R) and Voltage (V) (Ohm's Law):
Reference Data
| AWG Size | Max Amps (Chassis) | Max Amps (Transmission) | Typical Use |
|---|---|---|---|
| 30 AWG | 0.86 A | 0.14 A | Wire wrapping, signal trace |
| 24 AWG | 3.5 A | 0.58 A | Ethernet, Telephone |
| 20 AWG | 11 A | 1.5 A | Low power LED lighting |
| 16 AWG | 22 A | 3.7 A | Extension cords (Light) |
| 14 AWG | 32 A | 5.9 A | Household Outlets (15A) |
| 12 AWG | 41 A | 9.3 A | Household Outlets (20A) |
| 10 AWG | 55 A | 15 A | Water Heaters, AC units |
| 4 AWG | 135 A | 60 A | Large Battery Banks |
| 0 AWG | 245 A | 150 A | Main Service Entrance |