Parallel Resistor Calculator, Formula, Calculation with Example

Parallel Resistor Calculator

Resistors in parallel always result in an equivalent resistance that is less than the resistance of each individual resistor. On the other hand, resistors in series are equivalent to a resistor, Its resistance is the sum of each resistor.

If you think about it, the lower equivalent resistance for parallel resistors makes sense. Applying a voltage across a resistor causes a certain amount of current to flow.

If you add another resistor in parallel with the first resistor, you’ve opened a new channel through which more current can flow. No matter how high the resistance of the second resistor is, the total current flowing from the power supply will be at least slightly greater than the current through the single resistor. The higher the total current, the lower the overall equivalent resistance.

Multiple resistors in parallel are often used to create a small effective resistance when your desired resistance value is not readily available. This is handy when you need a specific resistance value and a suitable part is not readily available. For example, you can easily calculate the equivalent resistance when two identical resistors are in parallel.

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Parallel Resistor Formula:

Parallel Resistor formula is the equivalent parallel resistance 1/R (ohm) in ohms is equal to the one divided  by the parallel resistance 1/R1(ohm) in ohms and addition of the one divided by parallel resistance 1/ R2(ohm) in ohms and addition the  one divided by the resistance of individual resistors 1/Rn(ohm) in ohms.Hence the parallel resistance can be written as

1/R (ohm)= 1/R1(ohm) +  1/ R2(ohm) +…….. + 1/Rn(ohm)

R =is the equivalent parallel resistance in ohm

R1 , R2…Rn are the resistance of individual resistors numbered 1..n


Calculate the Resistance 60Ω ,30 Ω.Find the Resistance value?


R1 = 60 Ω

R2 = 30 Ω

By using formula

1/R = 1/R1 + 1/R2

Resistance (R) =1/60 +1/30

=20 ohms


Calculate the Resistance 44Ω , 18Ω.Find the Resistance value?


R1 = 44 Ω

R2 = 18 Ω

By using formula

1/R = 1/R1 + 1/R2

Resistance (R) =1/44 +1/18

=12. 77ohms


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