Calculate voltage from current and resistance, power and current, or power and resistance. This voltage calculator uses Ohm's Law and electrical power formulas to estimate volts, millivolts, kilovolts, current, resistance, and wattage.
Current and resistance:
Enter amps and ohms. The calculator uses V = I × R.
Power and current:
Enter watts and amps. The calculator uses V = P ÷ I.
Power and resistance:
Enter watts and ohms. The calculator uses V = √(P × R).
A voltage calculator helps estimate volts when you know current, resistance, or power.
It can help with electronics projects, resistor calculations, power supply planning, battery circuits, LED circuits, DC wiring estimates, and basic electrical troubleshooting.
Your result shows estimated voltage, millivolts, kilovolts, current, resistance, power, the formula used, load category, scenario comparisons, and a calculation summary based on the values entered.
Use V = I × R when you know current and resistance. Multiply amps by ohms to get volts.
Use V = P ÷ I. Divide watts by amps to estimate voltage.
Use V = √(P × R). Multiply watts by ohms, then take the square root.
No. Voltage is electrical pressure, while power is the rate of electrical work. Power is commonly calculated with P = V × I.