⚡ Voltage Calculator

Free Ohm's Law & Electrical Circuit Calculator Online

Calculate voltage, current, resistance, and power instantly. Professional electrical engineering tool for students and professionals.

What are you solving for?

Use our advanced voltage calculator to solve for voltage, current, resistance, or power using Ohm's Law formulas. Perfect for electrical engineering calculations and circuit analysis.

Voltage
V - Volts
🔋
Current
I - Amps
🛡️
Resistance
R - Ohms
💪
Power
P - Watts

Enter known values (any 2)

Amps
Ohms
Watts

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Ohm's Law & Electrical Power - Complete Guide

Learn the fundamentals of voltage calculation, Ohm's Law formulas, and electrical power calculations. Essential knowledge for electrical engineering and circuit analysis.

Ohm's Law

Ohm's Law states that the current through a conductor between two points is directly proportional to the voltage. This is true for many materials, over a wide range of voltages and currents, and the resistance and conductance of electronic components made from these materials remain constant.

V = I × R
R = V / I
Resistance
I = V / R
Current
V = I × R
Voltage
Where: V is voltage in Volts, R is resistance in Ohms, I is current in Amperes

Electrical Power

Power is the rate at which electrical energy is transferred by an electric circuit per unit time typically expressed in the SI unit of Watts. In resistive circuits, Joule's Law can be combined with Ohm's Law to produce alternative expressions for power dissipation.

P = V × I
P = V² / R
Power (Voltage)
P = I² × R
Power (Current)
P = V × I
Power (Basic)
Where: P is power in Watts

Ohm's Law Formula Wheel

Below is a formula wheel for Ohm's Law relationships between P, I, V, and R. To use the wheel, choose the variable to solve for in the middle of the wheel, then use the relationship for the two known variables within the cross section of the circle.

P
I
V
R
V = I × R
⚡ Voltage
I = V / R
🔋 Current
R = V / I
🛡️ Resistance
P = V × I
💪 Power
P = I²R
🔥 Power (I)
P = V²/R
⚡ Power (V)