To Find  Direct Current  Alternating Current  

Single Phase  TwoPhase* FourWire  Three Phase  
Amperes when Horsepower is known 
HP x 746
E x EFF 
HP x 746
E x EFF x PF x 2 
HP x 746
2 x E x EFF x PF 
HP x 746
E x EFF x PF x 1.73 
Amperes when Kilowatts are known 
KW x 1000
E 
KW x 1000
E x PF 
KW x 1000
2 x E x PF 
KW x 1000
E x PF x 1.73 
Amperes when "KVA" is known 
KVA x 1000
E 
KVA x 1000

KVA x 1000
E x 1.73 

Kilowatts 
E x I
1000 
E x I x PF
1000 
I x E x 2 x PF
1000 
E x I x 1.73 x PF
1000 
KilovoltAmperes "KVA" – 
I x E
1000 
I x E x 2
1000 
E x I x 1.73
1000 

Horsepower (Output) 
E x I x EFF
746 
E x I x EFF x PF
746 
I x E x 2 x EFF x PF
746 
E x I x EFF x PF x 1.73
746 
E = Voltage 
Note: Direct current formulas do not use (PF, 2, or 1.73)
 Single phase formulas do not use (2 or 1.73)
 Two phasefour wire formulas do not use (1.73)
 Three phase formulas do not use (2)
 * For threewire, two phase circuits the current in the common
conductor is 1.41 times that in either of the other two conductors.