Engineering
Ohm's Law Calculator
Enter any two compatible electrical values to calculate voltage, current, resistance, and power. Review current sensitivity across resistance scenarios, inspect a technical table, and export a professional PDF record.
Voltage0 V
Current0 A
Resistance0 ohms
Power0 W
Load sensitivity
Current and power at nearby resistance values
Power at fixed calculated voltageResistance scenario comparison
| Resistance | Voltage | Current | Power | Recommended minimum rating |
|---|
Circuit view
Voltage, current, resistance, and power circuit
The circuit card keeps the four Ohm's law quantities visible together.
Voltage, current, resistance, and power circuit
V0 V
R0 ohms
I0 A
Power load0 W
Recommended margin0 W
How to use Ohm's Law Calculator
- Choose which two electrical quantities are known, then enter those two values using compatible units.
- Review voltage, current, resistance, and power together because changing one value changes the full electrical relationship.
- Use the resistance scenario table to check how current and wattage rating change when the load resistance is lower or higher.
Calculator guide
Understanding Ohm's Law Calculator
Ohm's law links voltage, current, and resistance in a resistive DC model. Once any two values are known, the remaining electrical quantity and power can be calculated consistently.
Calculation method
How the calculation works
Voltage = current x resistance; power = voltage x current. Select the pair of known quantities. Apply V = I x R and the equivalent power relationships P = VI, P = I squared R, or P = V squared/R.
Ohm's law method
Electrical safety limits
Worked situations
Practical examples
- Calculate current from a known supply voltage and load resistance.
- Find resistance from measured voltage and current.
- Compare power dissipation as resistance changes at a fixed voltage.
Better inputs
Useful tips
- Keep units consistent before entering values.
- Check component power ratings with a suitable safety margin.
- Use measured operating values when temperature materially changes resistance.
Before relying on the result
Limitations and common mistakes
- The model assumes a simple resistive DC or RMS-equivalent load.
- Reactive impedance, phase angle, transients, and nonlinear devices are not modeled.
- This is not a substitute for electrical safety design or code compliance.
Reference
Key terms
- Volt
- Unit of electrical potential difference.
- Ampere
- Unit of electric current.
- Ohm
- Unit of electrical resistance.
- Watt
- Unit of electrical power.
Important note
Calculated from the entered values using the displayed engineering relationship. Confirm design values, load cases, safety factors, standards, and field conditions with a qualified professional.
Frequently asked questions
Which two values can I enter?
Choose voltage and current, voltage and resistance, or current and resistance.
How is power calculated?
Power is voltage multiplied by current after the missing quantity is solved.
Can resistance be zero?
No for this calculator. An ideal zero-resistance path would imply unbounded current in the simplified model.
Does this calculate AC power factor?
No. It does not model reactive impedance or phase angle.