Understanding Energy Terms and Formulas

PPL Electric Utilities occasionally gets questions from customers regarding terms and formulas used in the energy business. Below, we’ve outlined electrical conversion formulas for determining amperes, horsepower, kilowatts and kilovolt amperes when other factors are known.


For more information on energy terms, visit the U.S. Department of Energy’s online at http://www.eere.energy.gov/




Electrical Conversion Formulas for three-phase AC power:

  • E represents volts
  • I represents amps
  • Eff represents motor efficiency
  • PF represents power factor
  • If PF is not known, assume 0.85
  • If Eff is not known, assume 0.90

·To find Amps when Horsepower is known:
Amps = (hp × 746) ÷ (1.73 × E × Eff × PF)

·To find Amps when Kilowatts are known:
Amps = (kW × 1000) ÷ (1.73 × E × PF)

·To find Amps when Kilovolt Amperes are known:
Amps = (kVA × 1000) ÷ (1.73 × E)

·To find Kilowatts when Amps, Volts and Power Factor are known:
kW = (I × E × 1.73 × PF) ÷ 1000

·To find Kilovolt Amperes when Amps and Volts are known:
kVA = (I × E × 1.73) ÷ 1000

·To find Kilowatts when Kilovolt Amperes and Power Factor are known:
kW = (kVA × PF)

·To find Kilowatts when Horsepower and Eff are known:
kW = hp × 0.746 ÷ Eff

Electrical Conversion Formulas for single-phase AC power:

  • E represents volts
  • I represents amps
  • PF represents power factor
  • If PF is not known, assume 0.85
  • If Eff is not known, assume 0.90

·To find Amps when Horsepower is known:
Amps = (hp × 746) ÷ (E × Eff × PF)

·To find Amps when Kilowatts are known:
Amps = (kW × 1000) ÷ (E × PF)

·To find Amps when Kilovolt Amperes are known:
Amps = (kVA × 1000) ÷ (E)

·To find Kilowatts when Amps, Volts and Power Factor are known:
kW = (I × E × PF) ÷ 1000

·To find Kilovolt Amperes when Amps and Volts are known:
kVA = (I × E) ÷ 1000

·To find Kilowatts when Kilovolt Amperes and Power Factor are known:
kW = (kVA × PF)

·To find Kilowatts when Horsepower and Eff are known:
kW = hp × 0.746 ÷ Eff