Current Calculator
Calculate current, voltage, resistance, and power with our free electrical calculator. Use Ohm's Law and Watt's Law to solve for amps, volts, ohms, and watts. Perfect for electricians, engineers, students, and DIY electronics projects.
What Is Electrical Current?
Electrical current is the flow of electric charge through a conductor. It is measured in amperes (A), commonly called amps. Current is one of the fundamental electrical quantities, along with voltage (V) and resistance (R), and is governed by Ohm's Law.
This calculator helps you solve for any of the four fundamental electrical quantities — Current (I), Voltage (V), Resistance (R), and Power (P) — using Ohm's Law and Watt's Law. Simply select what you want to solve for, enter the known values, and get instant results.
How Does the Current Calculator Work?
The calculator uses the following fundamental electrical formulas:
Ohm's Law: V = I × R | I = V / R | R = V / I
Watt's Law: P = V × I | P = I² × R | P = V² / R
Where: I = Current (Amps), V = Voltage (Volts), R = Resistance (Ohms), P = Power (Watts)
Select what you want to solve for, enter the required values, and the calculator will compute the result. You can also enter an optional third value to cross-check the calculation.
Why Use This Current Calculator?
- Four Modes: Solve for current, voltage, resistance, or power.
- Ohm's & Watt's Laws: Uses both fundamental electrical laws.
- Optional Cross-Check: Enter a third value to verify your result.
- Unit Prefixes: Automatically use k, M, m, µ prefixes for large or small values.
- Free & Private: No registration, no data storage.
Understanding Electrical Units
- Current (I): Measured in amperes (A). 1 A = 1 coulomb per second.
- Voltage (V): Measured in volts (V). 1 V = 1 joule per coulomb.
- Resistance (R): Measured in ohms (Ω). 1 Ω = 1 volt per ampere.
- Power (P): Measured in watts (W). 1 W = 1 joule per second.
❓ Current Calculator FAQ
What is electrical current?
Electrical current is the flow of electric charge through a conductor. It is measured in amperes (A) and represents the rate at which charge flows past a point in a circuit.
What is Ohm's Law?
Ohm's Law states that the current through a conductor between two points is directly proportional to the voltage across the two points and inversely proportional to the resistance. Formula: V = I × R.
What is Watt's Law?
Watt's Law relates power, voltage, and current. Formula: P = V × I. It can also be expressed as P = I² × R or P = V² / R.
How do I calculate current?
Using Ohm's Law: I = V / R. If you know voltage and resistance, divide voltage by resistance to get current in amperes.
How do I calculate voltage?
Using Ohm's Law: V = I × R. Multiply current by resistance to get voltage in volts.
How do I calculate resistance?
Using Ohm's Law: R = V / I. Divide voltage by current to get resistance in ohms.
How do I calculate power?
Using Watt's Law: P = V × I. Multiply voltage by current to get power in watts.
What is the difference between AC and DC current?
DC (Direct Current) flows in one direction continuously. AC (Alternating Current) periodically reverses direction. This calculator works for both DC and AC circuits with resistive loads.
What is the difference between voltage and current?
Voltage is the electrical potential difference that drives current flow. Current is the actual flow of electric charge. Voltage is the "pressure," current is the "flow."
What is a resistor?
A resistor is an electrical component that resists the flow of current. It is measured in ohms (Ω) and is used to control voltage and current in circuits.
What is the unit of power in electrical circuits?
Power is measured in watts (W). One watt is equal to one joule of energy per second. In electrical circuits, power is the rate at which electrical energy is converted to another form.
How do I convert watts to amps?
Amps = Watts / Volts. If you know the power and voltage, divide power by voltage to get current in amps.
How do I convert amps to watts?
Watts = Amps × Volts. Multiply current by voltage to get power in watts.
What is the relationship between current, voltage, and resistance?
Ohm's Law describes the relationship: V = I × R. Current is directly proportional to voltage and inversely proportional to resistance.
What is the difference between a series and a parallel circuit?
In a series circuit, components are connected end-to-end, and the same current flows through all components. In a parallel circuit, components are connected across the same voltage source, and the current divides among the branches.
How do I calculate total resistance in a series circuit?
Total resistance in a series circuit is the sum of all individual resistances: Rtotal = R₁ + R₂ + R₃ + ...
How do I calculate total resistance in a parallel circuit?
Total resistance in a parallel circuit is: 1/Rtotal = 1/R₁ + 1/R₂ + 1/R₃ + ...
What is the best way to use this calculator?
Select what you want to solve for, enter the two known values, and optionally enter a third value to cross-check. The calculator will show the result and all equivalent values.