How to converted KW to KVA

Why we convert KW to KVA when we install the distribution transformer in domestic , industrial and other locations. where we need required load rating and transformer rating .

But AC load are resistative , inductive and capacative so voltage and current are not in phase both have phase difference this phase difference define by the lagging and leading power factor. 

AC power is the product of voltage . Current and power factor and it unit is watt so we calculate the in KW and MW.

Calculation of KW to KVA

Kw = kilo×voltage×current×pf

Pf = power factor

And

KVA = kilo ×voltage × current

Now converting kw to kva

Kilo × voltage × current × pf =  kilo × voltage × current × pf

Kilo × voltage × current = ( kilo × voltage × current × pf ) / pf

KVA = ( kilo × voltage × current × pf ) / pf

KVA = KW/pf

Similar we can  convert KW to KVA

KW = KVA × pf

Example :- Convert the load  20 KW into KVA  and power factor is 0.8.

KVA = kW/pf

KVA = 20/0.8

KVA = 25

If 20 kW load then transformer required 25 KVA.