EngineerHub.orgDrawing No. EH–EE–017 // Electrical Engineering
Ohm's Law Calculator
Reviewed August 2026
Solve voltage, current, resistance and power from any two known values, then estimate energy use and combine resistors in series or parallel.
What problem does this solve?
Solve voltage, current, resistance and power from any two known values, then explore energy use and series or parallel resistor combinations.
Inputs
Results
Series and parallel resistor helper
Background
For an ohmic component at constant conditions, V = IR. Rearranging gives I = V/R and R = V/I.
Power is P = VI. Combining with Ohm’s law gives P = I²R and P = V²/R.
Diodes, lamps, motors, batteries and many electronic devices are nonlinear or time-varying. Use the device characteristic or AC impedance where appropriate.
Frequently asked questions
Practical questions about inputs, assumptions and interpretation.
It describes the relationship V = IR for an ohmic conductor under constant physical conditions.
Combining P = VI with I = V/R gives P = V²/R.
For a purely resistive AC load using RMS values, yes. Reactive AC circuits require impedance and power factor.
Many materials change resistance with temperature, so a filament lamp is not perfectly ohmic during warm-up.