MasterTool

Ohm's Law Calculator

Solve voltage, current, resistance and power from two DC quantities.

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What this tool does

Solve voltage, current, resistance and power from two DC quantities. For purely resistive circuits; AC impedance and nonlinear components need a different model.

How to use the Ohm's Law Calculator

  1. Enter or select known quantities.
  2. Enter or select voltage (v).
  3. Enter or select current (a).
  4. Enter or select resistance (ohms).
  5. Read the calculated result; change any measurement to compare alternatives.

Formula

V=I×R; P=V×I; solve third quantity from the selected two
known
Known quantities
voltage
Voltage (V)
current
Current (A)
resistance
Resistance (ohms)

For purely resistive circuits; AC impedance and nonlinear components need a different model.

Worked example

For ohm's law calculator, the following measurements illustrate the exact method: Known quantities: vr; Voltage (V): 12; Current (A): 2; Resistance (ohms): 6.

Inputs

  • Known quantitiesVoltage and resistance
  • Voltage (V)12
  • Current (A)2
  • Resistance (ohms)6

Result

  • Voltage (V)12
  • Current (A)2
  • Resistance (ohms)6
  • Power (W)24

Results explained

Voltage (V)
Voltage (V) from the formula above. For purely resistive circuits; AC impedance and nonlinear components need a different model.
Current (A)
Current (A) from the formula above. For purely resistive circuits; AC impedance and nonlinear components need a different model.
Resistance (ohms)
Resistance (ohms) from the formula above. For purely resistive circuits; AC impedance and nonlinear components need a different model.
Power (W)
Power (W) from the formula above. For purely resistive circuits; AC impedance and nonlinear components need a different model.

Frequently asked questions

V=I×R; P=V×I; solve third quantity from the selected two

For purely resistive circuits; AC impedance and nonlinear components need a different model.

No. Electrical and HVAC results are estimates. Installation must comply with local codes and be checked by a qualified licensed professional.

Nameplate values, conductor temperature, power factor, efficiency, weather and actual installation conditions may differ from your entered assumptions.

Confirm units, manufacturer data and the formula's assumptions, then verify sizing with the equipment instructions and applicable local standards.