Ohm's Law Calculator
Solve Ohm's Law circuits instantly. Calculate voltage, current, resistance, or power given any two values. Handles prefixes and evaluates resistor ratings.
Circuit Values
Ohm's Law requires exactly two input values to calculate the other two. Fill in two fields, and leave the other two blank.
Resistor & Circuit Outputs
Ohm's Law Calculated Results
Resistor Wattage Rating Recommendation
Use at least a 1/8 Watt (0.125W) resistor.
Formula Derivation & Calculations
How Ohm's Law Calculator Works
Use our interactive tool to calculate electrical circuit variables with direct steps.
Select Known Variables
Identify the two electrical parameters that you already have values for.
Enter Electric Voltage
Input potential difference values in standard Volts or prefix multiples.
Input Current Amperage
Provide current flow parameters in Amperes or sub-units.
Ohm's Law Formulas
Calculate electrical parameters using these primary mathematical representations.
Set Ohmic Resistance
Resistance is calculated using Voltage divided by Current (R = V / I).
Determine Electric Power
Power in Watts is calculated by multiplying Voltage and Current (P = V * I).
Dynamic Resistor Safety
Evaluate component power dissipation against safety limits to prevent overheating.
Chronological Step Verification
Examine complete, sequential formulas and algebraic workflows for each calculation.
Frequently Asked Questions About Ohm's Law
Frequently Asked Questions
Is this Ohm's Law calculator free?
Yes. Calculate unlimited electronic circuit parameters with no registration.
What are the four parameters in Ohm's Law?
The four parameters are Voltage (V), Current (I), Resistance (R), and Power (P).
Can I calculate resistor safety ratings?
Yes. Check wattage safety parameters to prevent thermal failures.
Do you record my circuit designs?
No. All electronic calculations run locally in your browser to maintain privacy.