Voltage Current Resistance Calculator
Calculate voltage, current, resistance, and power relationships for linear power paths, supply checks, and load calculations. Choose a direct calculation mode or enter any two known electrical values to solve the complete relationship with automatic engineering-unit conversion.
Engineering tool
Voltage Current Resistance Calculator
Solve voltage, current, resistance, and power relationships with engineering-unit conversion.
Result console
- Voltage
- 12V
- Current
- 2A
- Resistance
- 6Ω
- Power
- 24W
Electrical relationship summary
Formula: V = I × R
Voltage drives current through resistance; electrical power is P = V × I.
Formula reference
Voltage, Current, Resistance, and Power Formulas
Use volts, amperes, ohms, and watts as base SI units.
Voltage: V = I × RCurrent: I = V / RResistance: R = V / IPower: P = V × IPower: P = I² × RPower: P = V² / RVariable definitions
- V
- voltage in volts
- I
- current in amperes
- R
- resistance in ohms
- P
- electrical power in watts
Worked Example
With I = 2 A and R = 6 Ω:
V = 2 × 6 = 12 V. Power = 12 × 2 = 24 W.
The electrical relationship summary is 12 V, 2 A, 6 Ω, and 24 W.
Engineering Notes
- Use this page for supply, load, and power-path relationship checks.
- Power dissipation should always be verified after voltage and current are known.
- Temperature changes may affect resistance.
- Measure voltage under load whenever possible.
- For resistor-centered value selection, use the Resistors Ohm's Law Calculator.
Support reference
FAQ
What does the voltage current resistance calculator solve?
It solves voltage, current, resistance, and power relationships for linear resistive power paths using V = I × R and P = V × I.
How do you calculate voltage from current and resistance?
Multiply current in amperes by resistance in ohms: V = I × R.
How do you calculate resistance from voltage and current?
Divide voltage in volts by current in amperes: R = V / I.
How do you calculate current from voltage and resistance?
Divide voltage in volts by resistance in ohms: I = V / R.
When should I use this instead of the resistor Ohm's Law calculator?
Use this Power calculator when the task is power-stage, supply, or load relationship checking. Use the Resistors Ohm's Law Calculator when the task is centered on resistor selection or resistor circuit troubleshooting.
Documentation
Related Engineering Resources
Guides and lookup references linked to this tool.
Engineering Guide
Understanding Electrical Power
Learn electrical power fundamentals, including voltage, current, resistance, watts, energy, Ohm's law, DC and AC power, efficiency, power dissipation, and practical calculations.
18 min · Beginner
Engineering Guide
Ohm's Law for Resistor Design and Circuit Checking
Apply Ohm's law to resistor selection, current and voltage checks, power rating, tolerance, temperature effects, measurement, and troubleshooting.
17 min · Beginner
Engineering Guide
Engineering Unit Conversions for Electronics
Learn engineering unit conversions for electronics, including SI prefixes, powers of ten, engineering notation, resistance, capacitance, inductance, voltage, current, power, energy, frequency, time, PCB units, and common conversion mistakes.
22 min · Beginner
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