Series Resistor Calculator
Add series resistances and calculate circuit current, voltage drops, and power.
Rtotal = R₁ + R₂ + …Calculations stay in your browser. Share links contain the input values you choose to share.
How to use this calculator
- Enter two or more resistor values and their units.
- Add up to 12 series resistors.
- Read the total resistance.
- Enable current and voltage drops, then enter the supply voltage.
A quick worked example
A 1 kΩ resistor in series with a 2 kΩ resistor gives 3 kΩ. Across 12 V, the common current is 4 mA. Voltage drops are 4 V and 8 V, with total power dissipation of 48 mW.
A few useful answers
What stays the same in a series circuit?
The same current flows through every resistor in a single series path. Voltage divides in proportion to each resistance.
Is total resistance higher than each individual resistor?
Yes. With positive resistor values, the total is the sum of all resistances and is greater than any individual resistance.
How is resistor power calculated?
Each resistor dissipates I² × R. The calculator reports each dissipation and their total; choose actual component ratings with a suitable design margin.
Model & assumptions: Ideal DC resistors connected in one continuous path with no intermediate loads. Wiring resistance, tolerances, and source limits are not modeled.
Electronics Tools & Calculator
Also available for iOS, Android, and Windows.
