Resistors in series formula
A series circuit is characterized by a common current that flows through all of the resistors - there is only one path the current can follow. The equivalent resistance for this kind of circuit is a sum of all individual resistances:
Ris the equivalent series resistance
R₁, R₂, ... Rnare the resistances of individual resistors numbered
The units of all values are Ohms (symbol: Ω). 1 Ohm is defined as electrical resistance between two points that, when applied with a potential difference of 1 volt, produces a current of 1 ampere. Hence,
1 Ω = 1 V / 1 A or, in SI base units,
Ω = kg·m²/(s³·A²).
The formula for calculating equivalent resistance in a series circuit is similar to that for equivalent inductance in a series circuit.
How to calculate series resistance
- Establish the values of resistance for all resistors connected in series. For example, you can use three resistors of
3 Ω, and
6 Ω, respectively.
- Input these values in our series resistor calculator.
- Read the result. In this example,
R = 4 + 3 + 6, hence R =
13 Ω. Notice that the equivalent resistance is higher than any of the individual values for resistors in series.
Other uses of the series resistor calculator
The principle is the same as when determining capacitance in parallel or induction in series - you can use it for these calculations too. Just remember that the units are not the same!
If you would like to find out the value of power dissipated in the resistor, try the power dissipation calculator. You can also check out our wheatstone bridge calculator to learn how to measure unknown resistance.