Ohm's Law Calculator
The fundamental principle of electronics, simplified. Solve for any variable in an electrical circuit—Voltage, Current, or Resistance—using our interactive 3-way solver.
Result
Volts
V = I × R
Voltage is current multiplied by resistance.
I = V / R
Current is voltage divided by resistance.
R = V / I
Resistance is voltage divided by current.
Ohm's Law Concepts
Voltage (Potential Difference)
The "pressure" that pushes electric charge through a conductor. Measured in Volts (V).
Current (Flow)
The rate at which charge flows through a point in a circuit. Measured in Amperes (A).
Resistance (Opposition)
The measure of the opposition to current flow in an electrical circuit. Measured in Ohms (Ω).
Quick Tips
High resistance limits the amount of current that can flow for a given voltage.
Increasing voltage will increase the current flow if resistance stays constant.
Short circuits occur when resistance is near zero, causing a massive surge in current.
In a series circuit, total resistance is the sum of all individual resistances.
What is Ohm's Law?
Named after German physicist Georg Ohm, this law states that the current passing through a conductor between two points is directly proportional to the voltage across the two points.
In simple terms, it describes how much current will flow through a component based on how much "push" (voltage) is applied and how much the component "resists" that flow.
Practical Usage
Circuit Design
Selecting the right resistors to protect LEDs and components.
Power Planning
Determining current draw for household appliances.
Troubleshooting
Identifying short circuits or faulty components by measuring resistance.
The Ohm's Law Triangle
A popular way to remember the formulas is the **V-I-R Triangle**. By covering the letter you want to find, the remaining letters show the calculation required:
- Cover V: You see I × R
- Cover I: You see V / R
- Cover R: You see V / I
Frequently Asked Questions
What is an Ohm (Ω)?
The Ohm is the SI unit of electrical resistance. It is named after Georg Simon Ohm. 1 Ohm represents the resistance that allows 1 Ampere to flow when 1 Volt is applied.
Why is current measured in Amps?
Amperes (named after André-Marie Ampère) measure the number of electrons passing through a point per second (roughly 6.24 quintillion electrons!).
What happens if resistance is zero?
Theoretically, current would become infinite. In the real world, this is called a 'short circuit,' which causes wires to heat up rapidly and can trigger fuses or cause fires.
Can I use this for AC circuits?
Yes, but for simple resistive loads (like heaters). For inductive or capacitive loads, you need to consider 'Impedance' (Z) instead of just resistance.