Ohm’s Law & Electrical Power Calculator

Calculate Voltage (V), Current (I), Resistance (R), and Electrical Power (P) across DC circuits.

Configurable Calculation Inputs

Solve For: select (Default: voltage_current)
Primary Parameter: number (Default: 120)
Secondary Parameter: number (Default: 10)

Mathematical Formula: Ohm’s Law & Joule’s Power Law

          V = I * R ; P = V * I = I² * R = V² / R
        

Fundamental electrical equations relating electric potential (Volts), charge flow rate (Amps), impedance (Ohms), and power dissipation (Watts).

Comprehensive Guide & Context

Preventing Overload on Domestic Breakers

A standard 15-amp, 120-volt residential breaker can sustain up to 1,800 watts peak, but the 80% continuous load rule advises keeping ongoing draws below 1,440 watts.

Worked Calculation Examples

US Household 120V Circuit with 15A Draw

120 Volts with 15 Amps current.

Result: 1,800 Watts (8.00 Ω Resistance)

Frequently Asked Questions

What is the relationship between Watts and Amps?

Watts is total electrical power (Watts = Volts * Amps). To find Amps needed for a device, divide its Wattage by the circuit Voltage.