Voltage Calculator
Calculate voltage using Ohm's Law (V = IR), from power and current (V = P/I), or from power and resistance (V = √(PR)).
How to Calculate Voltage
Choose Calculation Method
Select from three methods: V = IR (Ohm's Law), V = P/I (from power), or V = √(PR) (from power and resistance).
Enter Known Values
Input the values you know - current and resistance, power and current, or power and resistance.
Get Instant Results
Click calculate to see voltage plus secondary results like power or resistance.
Key Features of This Voltage Calculator
**Three Calculation Methods**
Calculate voltage using Ohm's Law (V=IR), from power and current (V=P/I), or from power and resistance (V=√PR).
**Multiple Unit Options**
Display results in Volts (V), Millivolts (mV), or Kilovolts (kV) for any application.
**Secondary Calculations**
Each method also computes related values like power or resistance for complete circuit analysis.
**Free & Educational**
Perfect for students, electricians, and hobbyists learning electrical fundamentals.
Frequently Asked Questions
What is Ohm's Law?
Ohm's Law states that voltage equals current times resistance (V = I × R). It's the fundamental relationship in electrical circuits discovered by Georg Ohm in 1827.
How do I calculate voltage from power?
If you know power and current, use V = P/I. If you know power and resistance, use V = √(P × R). Both formulas derive from the power equation P = VI.
What is the difference between AC and DC voltage?
DC (direct current) voltage flows in one direction (batteries). AC (alternating current) voltage reverses direction periodically (wall outlets). This calculator works for both types.
How do I convert between voltage units?
1 kilovolt (kV) = 1,000 volts. 1 volt = 1,000 millivolts (mV). To convert V to kV, divide by 1,000. To convert V to mV, multiply by 1,000.
What voltage is dangerous?
Voltages above 50V AC or 120V DC can be dangerous. Always follow safety protocols when working with electrical circuits. Consult a qualified electrician for high-voltage work.
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