Ohm's Law: Calculators Before clicking for the answer, enter numbers into the equation you wish to use to calculate for Current, Power, Resistance, or Voltage. • Current (I) • Power (P) • Resistance (R) • Voltage (E) • Ohm's Law Pie Chart Calculate for Current (I) I = P / E Power Voltage   Current   Watts Volts   Amps   I = Square Root of (P / R) Power Resistance   Current   Watts Ohms   Amps   I = E / R Voltage Resistance   Current   Volts Ohms   Amps   Calculate for Power (P) P = I 2 x R Current Resistance   Power   Amps Ohms   Watts   P = E x I Voltage Current   Power   Volts Amps   Watts   P = E 2 / R Voltage Resistance   Power   Volts Ohms   Watts   Calculate for Resistance (R) R = P / I 2 Power Current   Resistance   Watts Amps   Ohms   R = E / I Voltage Current   Resistance   Volts Amps   Ohms   R = E 2 / P Voltage Power   Resistance   Volts Watts   Ohms   Calculate for Voltage (E) E = I x R Current Resistance   Voltage   Amps Ohms   Volts   E = P / I Power Current   Voltage   Watts Amps   Volts   E = Square Root of (P x R) Power Resistance   Voltage   Watts Ohms   Volts