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Voltage Calculator

Instantly calculate voltage using current, resistance, and power with our advanced calculator
DC Voltage
AC Voltage
Voltage Divider

DC Voltage Calculator

Voltage Equations:
V = I × R   (Voltage = Current × Resistance) V = P / I   (Voltage = Power ÷ Current) V = √(P × R)   (Voltage = Square root of Power × Resistance)
1A
0.5A
100Ω
1kΩ
60W
Enter any two values to calculate voltage
Auto-calculate as you type
0 V
0 V 50 V 100 V 150 V 200+ V

Note: The voltage meter visualization shows relative magnitude up to 200V.

AC Voltage Calculator

AC Voltage Equations:
Vrms = Irms × Z   (Voltage = Current × Impedance) Vrms = P / (Irms × PF)   (Voltage = Power ÷ (Current × Power Factor)) Vpeak = Vrms × √2   (Peak Voltage = RMS Voltage × √2)
1A
50Ω
120W
Enter values to calculate AC voltage
0 V
0 V 120 V 240 V

Note: For AC voltage, the meter shows RMS voltage. Peak voltage is √2 times the RMS value.

Voltage Divider Calculator

Voltage Divider Equation:
Vout = Vin × (R2 / (R1 + R2))
Enter values to calculate output voltage

Note: The circuit diagram updates automatically as you change resistor values.

Understanding Voltage Equations

Voltage (V) is the potential difference between two points in a circuit. You can calculate it using three equations, depending on which quantities you know:

Example 1: Using V = I × R

A circuit has a current of 2 A and a resistance of 10 Ω. What is the voltage?

Solution: V = 2 × 10 = 20 V

Example 2: Using V = P / I

A device consumes 60 W of power with a current of 5 A. What is the voltage?

Solution: V = 60 / 5 = 12 V

Example 3: Using V = √(P × R)

A resistor has a resistance of 16 Ω and dissipates 64 W. What is the voltage across it?

Solution: V = √(64 × 16) = √1024 = 32 V

Example 4: Voltage Divider

A voltage divider has R1 = 1 kΩ and R2 = 3 kΩ with an input voltage of 12 V. What is the output voltage?

Solution: Vout = 12 × (3000 / (1000 + 3000)) = 12 × 0.75 = 9 V