How to use the Ohm's Law Calculator
Estimate current from voltage (v), resistance (r) with the Ohm's Law Calculator. It includes Current from V & R, Voltage from I & R, Resistance from V & I, Power from V & I, Current from P & V, Resistance from P & I workflows, so choose the one that matches the values you actually know. Use it to check a practical estimate, paying close attention to the selected units and assumptions.
Step by step
- For the Ohm's Law example, select Current from V & R and enter voltage (v), resistance (r). Keep each value in the unit displayed beside its field.
- Review the selected Ohm's Law workflow and inputs, then read current in the result panel.
- Change one Ohm's Law assumption at a time to compare scenarios. Use Reset to restore this tool's worked example values.
How the calculation works
Selectable Ohm's-law and electrical-power equations.
Worked example
To reproduce the Ohm's Law worked example, reset the calculator. Select the Current from V & R workflow. Use voltage (v) 12 V; resistance (r) 6 Ω. The result is current of 2 A. I = V ÷ R. Review the displayed units before comparing the result.
Understanding the result
The Ohm's Law reports current. Use it to check a practical estimate, paying close attention to the selected units and assumptions. Check the entered units and assumptions before using the result for purchasing, construction, engineering, or safety decisions.
How to check the answer
Check the Ohm's Law result by reversing the conversion or recomputing current from voltage (v), resistance (r). For construction, electrical, weather, or purchasing decisions, compare the result with the applicable specification or professional guidance.
Common questions
What does the Ohm's Law calculate?
Estimate current from voltage (v), resistance (r) with the Ohm's Law Calculator.
Which inputs does the Ohm's Law example use?
The worked example uses voltage (v), resistance (r) in the Current from V & R workflow. Other workflows can show different fields. Keep the chosen workflow and units with the result when comparing calculations.
Is the Ohm's Law result exact?
Check the entered units and assumptions before using the result for purchasing, construction, engineering, or safety decisions. Recheck voltage (v), resistance (r) and use current only for a decision where that level of precision is appropriate.