Ohm's Law Calculator
Solve Ohm’s law and the power equations: enter any two of voltage, current, resistance and power to find the other two.
Your inputs
Results
Current
2 A
- Voltage
- 12 V
- Resistance
- 6 Ω
- Power
- 24 W
✓Exact calculation — rounded only for display
Show calculation steps
- V = I × R, P = V × I = I²R = V²/R
What this calculator does
Ohm’s law links voltage, current and resistance in a resistive circuit; the power equations add watts.
Formula and method
Worked example
Calculated by this tool with its default inputs:
Inputs
- Voltage V (volts): 12
- Current I (amperes):
- Resistance R (ohms): 6
- Power P (watts):
Results
- Voltage: 12 V
- Current: 2 A
- Resistance: 6 Ω
- Power: 24 W
How to read the results
Doubling voltage across a fixed resistance doubles current and quadruples power.
Assumptions and limitations
- Applies to resistive (ohmic) loads; reactive AC loads need impedance and power factor.
- Educational estimate. Electrical, structural and safety-critical work must follow local codes and be designed or checked by a qualified professional.
These are educational estimates. Electrical, structural and other safety-critical work must comply with local codes and be designed or checked by a qualified professional.
Questions
Which two values should I enter?
Any two; leave the other two blank.
Methodology and verification
- Result type
- Exact mathematical calculation (rounded only for display)
- Formula version
- 1.0
- Automated verification
- 4 reference and validation test cases, checked against independently computed values. The site cannot be built if any of them fail.
- Editorial review
- Awaiting human editorial review. The explanation was drafted with AI assistance; the formula and examples are verified by the automated tests above.
Privacy
Everything you enter is calculated in this browser and is not sent to Numerith or anyone else. Inputs are added to a share link only if you choose to include them. Privacy policy