Real Power VS. Reactive Power: Get To Know The Differences

The significant difference between real power and reactive power is that real power is the true power drawn by the load because of the energy being dissipated as heat. In contrast, reactive power is the amount of power that continually moves and back between the source and load. Reactive power is theoretically considered useless power. Here we look at other differences in detail. 

Real Power VS. Reactive Power

Differences Between Real Power And Reactive Power Based On Specific Characteristics:


According to the AC electrical schemes, the quantity of power used to create productive work is called ‘real power’ or ‘true power’ or ‘active power.’ It is the useful power that is drawn by the load because of energy being dissipated as heat. Reactive power is the quantity of power that continually moves and back between the source and load, meaning the power that is useless in an AC circuit or system. 


Watt(W) is a standard unit that is reserved for real power. It is usually measured in megawatts (MW) and kilowatts (KW) in electrical power systems.  On the other hand, reactive power is a form of power expressed by unit volt-ampere reactive (var) in electrical power systems. Even though all form of power is generally expressed in watts, that’s not the case with reactive power.

Symbol And Formula 

Real power or active power is represented by the capital letter “P.  On the other hand, reactive power is symbolized by the capital letter “Q.”  Real power is a power that is dissipated to the load and is later turn into some form of energy.  The formula for real power is P= VI cos ϕ, where ϕ is the shift between current and voltage. While the formula for reactive power is Q = VI sin ϕ, whereby “I sin ϕ” signifies the current is not working with voltage. 


Real power is established in several physical forms, such as mechanical form, acoustic waves, or electromagnetic radiation. A good example is a wheel-barrow, a small hand-propelled with one wheel and is intended to be pushed by one person. 

The real power here is the effort employed on the wheel for carrying items from one destination to another, which is the actual work. In this case, reactive power is the unreal power that is useless by itself, but it retains the wheel-barrow in the lifted position. Reactive power is mostly used for voltage control in various industrial settings to overcome variations in voltage levels.

Comparison Between Real Power And Reactive Power 

Basis Of Comparison Active Power Reactive Power 
Definition The real power is the power that is dissipated in the circuitA power that moves back and forth between the load and the source 
Formula P= VI cos ϕQ = VI sin ϕ
Units Watts, Kw, MW VAr, KVAr, MVA 
Measurement instrument Wattmeter VAr meter 
Role in DC Circuit Real power is equal a reactive power. This means only real power exists.Absence of reactive power in the DC circuit. This is due to the zero-phase angle between current and voltage
Role in AC Circuits Real power is vital to create heat and utilize the electric and magnetic field produced by reactive power Reactive power plays a significant role in AC Circuits to create magnetic and electric fields
Behavior in a purely resistive circuit Resistors dissipate all circuit power Purely resistive circuit has no reactive power
Behavior in a purely capacitive circuit Real power is zeroLeading Vars 
Applications Real power is used to generate light, torque heat, among others, in electrical appliances and machines This power is useful for measuring the power factor and producing electric flux, magnetic flux, the electric and magnetic field in transformers, motors, ballasts, etc. 

What Is Real Power In Life?

The real power comes to existence when someone loves what he/she does; when what someone does aligns with his/her values and follow his/her instinct and creativity. In real power, someone is motivated, focused, and disciplined.

Why Do You Use A Power Factor?

Improving the power factor might improve voltage to equipment, minimize power losses, maximize current-carrying capacity, and reduce electric bills. PF correction capacitors behave like reactive generators. This will aid in offsetting the non-working power used by inductive loads, hence improve the power factor.


The real power does a useful task in the circuit, while reactive power is an imaginary power that cannot do any practical work. Therefore, you can always minimize or get rid of reactive power by applying a capacitor tank. 

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