Parallel Resistor Calculator

Enter any two of the following values and press the Calculate button.

Enter your values:

Resistor Ra:
Resistor Rb:
Parallel Resistance Rp:
Parallel Resistor Calculator

The parallel resistance calculator online calculator can calculate the resistance value of 2 to 4 resistors connected in parallel. The units should be consistent in the parallel resistance calculation formula.

The formula for calculating the resistance of a parallel resistor is: 1/R and =1/R1+1/R2+1/R3+...1/Rn

For example: the resistance R of four resistors 10Ω, 10Ω, 100Ω, and 100Ω connected in parallel is:


1/R and=22/100

R and≈4.5Ω

Another example: the resistance R of two resistors of 820Ω and 1.5kΩ connected in parallel is:

1/R and=1/820+1/1500

1/R and=116/61500

R and≈530.2Ω

Two typical applications of parallel resistors:

1. There is no suitable resistor: When you cannot find a resistor with a suitable resistance value, you can obtain it by connecting multiple resistors in parallel.

2. The resistor power does not meet the requirements: For example, if a 1W 25Ω resistor is needed in the circuit but is not available on hand, four 1/2W 100Ω resistors can be used in parallel to replace it. Considering the even power distribution, four 1/2W resistors with a resistance of 100Ω can be used instead. The resistance values of the resistors should be as consistent as possible.

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