Created By : Vaibhavi Kumari

Reviewed By : Rajashekhar Valipishetty

Last Updated : May 14, 2023

Using the resistance of the resistors, our Series Resistor Calculator calculates the equivalent resistance or missing resistor value in a series circuit. To check the equivalent resistance in a short period, simply enter the needed input information and click the calculate button.

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Resistor 1 (R1)
Resistor 2 (R2)

Formula for Resistors in Series

A resistor is a component that controls or limits the passage of current in a circuit. Ohm is its SI unit. In a circuit, these resistors can be wired in series or parallel. A common current runs through all of the resistors if they are connected in series. As a result, overall resistance equals the sum of individual resistances.

The equivalent resistance formula is as follows R = R₁ + R₂ + R₃ + . . . Rn

Missing Resistance formula is R₂ = R - (R₁ + R₃ + . . . Rn)

  • Where, R = equivalent series resistance
  • R₁, R₂, R₃, . . . Rn = resistances of individual resistors

How to Calculate Resistance in Series Circuit?

Examine the step-by-step procedure for calculating the equivalent resistance in a series circuit. Follow these methods to acquire the desired result quickly.

  • Step 1: Obtain the resistances of all series-connected resistors.
  • Step 2: To find the total resistance, add all of the resistances together.

How to Use the Series Resistor Calculator?

The steps for using the Series Resistor Calculator are as follows

  • Step 1: Enter the unknown resistance values of all series-connected resistors.
  • Step 2: To obtain the result, select "Calculate the Unknown" from the drop-down menu.
  • Step 3: Finally, the output field will display the circuit's equivalent resistance.

You may use the same method to calculate capacitance in parallel or induction in series. Just keep in mind that the units are different! Use the power dissipation calculator to figure out how much power is absorbed by the resistor.

Series Resistor Examples

Question 1: Find the total resistance in the circuit if four resistors are connected in series and their resistances are 5 Ω, 15 Ω, 20 Ω, 25 Ω?


Given: R₁ = 5 Ω, R₂ = 15 Ω, R₃ = 20 Ω, R₄ = 25 Ω

Equivalent series resistance R = R₁ + R₂ + R₃ + R₄

R = 5 + 15 + 20 + 25

= 65 Ω

Hence, the equivalent series resistance is 65 Ω.

For more concepts check out to get quick answers by using this free tool.

FAQs on Series Resistors

1. What are series resistors and how do you use them?

When you connect resistors in series, the current flowing through each resistance is the same. In other words, in a series circuit, the current is constant at all places. The sum of all the individual resistances in a series of resistors equals their total resistance.

2. What is the value of a resistor?

A resistor is a device that prevents electrical current from flowing. The larger a resistor's value, the more it inhibits the current flow. A resistor's value is measured in ohms and is referred to as its resistance.

3. Is it true that resistance increases when connected in series?

When you connect resistors in series, the overall resistance always goes up. Because the current must travel through each resistor one at a time, adding another resistor increases the resistance already there.

4. What's the difference between a series and a parallel capacitor?

Capacitors are considered to be in series when they are connected one after another. By summing the reciprocals of the individual capacitances and taking the reciprocal of the sum, the total capacitance of capacitors in series may be calculated.

5. What is the series combination?

Two or more resistors are said to be connected in series when they are connected end to end in a straight line. The sum of the individual resistances is equal to the total resistance of any number of resistances connected in series.