Circuit Equivalent Resistance Calculator

equivalent resistance calculator

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How to use Details

Enter resistor values as how they arranged series, parallel or in combination.

This Online Equivalent resistance calculator automates the cumbersome process of multiple times calculating resistance of series, parallel blocks in a single circuit. Find the total resistance of resistor circuit in a effortless way.

Resistors & NotationsIn SeriesIn Parallel
A, BA + BA | B
A, B, C, DA+B+C+DA | B | C | D
In Combination Example A | B | ( C + D )

Basic Circuit Text forms

resistors in series
  resistors in series
resistors in parallel
  resistors in parallel
resistors in parallel and series combination
resistors in combination

Use bracket pair whenever needed. See Example circuits below.

This calculator is a must have tool for students, professors and engineers, who are working on electronic circuit related projects. Also one can confirm or verify the calculated equivalent resistance value here.

Our circuit equivalent resistance calculator also can be used as both parallel resistor calculator and series resistor calculator.

Also see our Irregular 4-Side Object Area Calculator at fineducalcs.

Calculator Components Details

Series Parallel Combination Input Bar

Top most input bar in the calculator, Inputted using its below buttons or directly a series or parallel block inserted. Numeric values can be entered using keyboard.

Block Input Bar

The second input bar. Series or parallel values should be entered separating with space. The Resistors values inserted into combination bar (top) as a single block using its below buttons. Block directly inserted into position where cursor is there.


To insert nested blocks, give a extra space in the block input bar for a nested block. Place the cursor nested block position in combination bar, insert the block from block input bar. Repeat the process for multiple nested blocks.

Example circuit and its Text form

Here are few series and parallel combination circuits, it will help in converting the circuit into Text form, which you are going to calculate resistance.

equivalent resistance calculator
         Circuit and its Text form

How to use fineduCalcs Circuit Equivalent Resistance Calculator

  1. Have the circuit with resistors that can be written in series and parallel combination. Otherwise use Kirchhoff’s rules to calculate total resistance.
  2. Make sure all resistors resistance value is known.
  3. First identify all parallel type resistor arrangement and write them into text form.
  4. Add all series type resistor arrangement to the already written text form.
  5. Input the text form in the calculator and get circuit equivalent resistance instantly.



It’s a property of substance to oppose the flow of electrical current through it. Specified in units of Ohms.

Equivalent Resistance formula

Series Resistance formula:

All resistors are connected in a single loop. Equivalent resistance is addition of all Resistance values.

R(Eq) = R1 + R2 + R3 + . . . . .

Parallel Resistance formula:

The resistors are connected in separate branches. Equivalent resistance is Inverse of sum of inverse of every resistor value.

R(Eq) = 1 / (1/R1 + 1/R2 + 1/R3 + . . . . .)