Convert electrical resistance with current or power into voltage, then review related values, steps, units, formulas, and exportable engineering results instantly.
Resistance alone cannot determine voltage. Current or power is also required.
Resistance does not become voltage by itself. A second electrical quantity is required. In most circuits, current supplies that missing information. Ohm’s Law states that voltage equals current multiplied by resistance. This calculator applies that relationship while managing common engineering units automatically. Enter resistance in ohms, kilo-ohms, or larger units. Then enter current in amperes, milliamperes, or microamperes. The calculator converts values to base SI units before solving.
Sometimes current is unknown, but power is available. Voltage can then be found from resistance and power. The relationship is voltage equals the square root of power multiplied by resistance. The calculator also finds the corresponding current. This is useful when checking resistor loads, heaters, lamps, and other resistive devices. Power must remain nonnegative, while resistance must stay greater than zero.
Electrical calculations often mix volts, millivolts, amps, milliamps, ohms, and kilo-ohms. Mixing prefixes without conversion can produce errors by factors of thousands or millions. This tool performs those conversions internally. It also reports voltage in several units, displays resistance in ohms, and calculates conductance in siemens. The step display shows substituted values so each result can be checked.
Use this calculator for resistor selection, sensor circuits, LED calculations, test equipment, power supplies, and basic electronics troubleshooting. It can also rearrange Ohm’s Law to find current, resistance, or power. The reference table below provides quick examples. CSV and PDF downloads make results easier to save, compare, or include in technical notes. Always verify component ratings before applying calculated values in real hardware.
For reliable design work, compare the calculated voltage with resistor wattage, supply limits, wire ratings, and equipment tolerances. Real components can change resistance with temperature. Measuring instruments also add small errors. Use calculated values as a design guide, then confirm important circuits with appropriate meters and manufacturer specifications before operation.
| Resistance | Current | Voltage | Power | Formula |
|---|---|---|---|---|
| 100 Ω | 0.5 A | 50 V | 25 W | V = I × R |
| 1 kΩ | 10 mA | 10 V | 0.1 W | V = I × R |
| 4 Ω | 2 A | 8 V | 16 W | V = I × R |
| 100 Ω | 0.5 A | 50 V | 25 W | V = √(P × R) |
| 220 Ω | 20 mA | 4.4 V | 0.088 W | V = I × R |
No. Resistance requires current or power before voltage can be calculated.
Use current for Ohm’s Law, or use power for the square-root relationship.
Multiply current in amperes by resistance in ohms.
Yes. Use V = √(P × R), with power in watts.
Yes. The calculator converts selected prefixes automatically before solving.
At constant current, Ohm’s Law makes voltage directly proportional to resistance.
Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.