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Electric Current Calculator

Calculate electric current (Amperes) from power and voltage or voltage and resistance.

1. Enter your numbers  →  2. Check the answer  →  3. Read the steps before you trust it

V
W
0-1

1.0 for DC & heaters; 0.8-0.9 for motors

Calculated Electric Current

Current (I)
12.5A

Required circuit carrying amperage

Associated Power (P)
1,500W
Recommended Continuous Conductor (125%)
15.625A

Minimum continuous ampacity threshold (NEC 210.19)

Step-by-Step Engineering Calculation

  1. 1Formula: I=PV×PFI = \frac{P}{V \times \text{PF}}
  2. 2I=1500 W120 V×1.0=12.50 AI = \frac{1500\text{ W}}{120\text{ V} \times 1.0} = \mathbf{12.50\text{ A}}

Formula & Theory

I = P / V | I = V / R

Computes electric current flow rate in Amperes based on power and voltage or circuit impedance.

Variable Definitions
I:
Current (Amperes (A)) – Electrical current flow
P:
Power (Watts (W)) – Operating wattage
V:
Voltage (Volts (V)) – Supply voltage

Worked Engineering Example

1500W Space Heater

A 1500W electric heater connected to a 120V household receptacle.

Inputs:
  • Power: 1500 W
  • Voltage: 120 V
Result: Current = 12.50 A

Key Assumptions

  • •Linear resistive load under steady-state operating conditions.

Limitations & Safety Scope

  • •Motor inrush currents can be 4 to 8 times nominal running current during startup.

Frequently Asked Questions

How do I calculate amperage for a 120V circuit?

Divide appliance wattage by 120V: Amps = Watts / 120V.

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Educational & Reference Notice: This calculator provides technical estimates based on standard physical formulas. Actual electrical installation, protective device sizing, and conductor selection must be verified against the applicable electrical code (NEC, IEC, CEC) by a licensed electrician or qualified professional engineer.