Resistors in Series Calculator
Add series resistor values and optionally calculate circuit current, voltage drops and power, using a common ohm, kilohm or megohm unit.
Add the values of resistors connected in a single series path. If you also provide the applied voltage, the calculator finds the common current and each component’s voltage drop and power. A component table lets you compare how the supply voltage is shared without assuming every resistor has the same value.
How to use this tool
- Enter each resistor value, using spaces, commas or new lines as separators.
- Choose one resistance unit for the whole list.
- Enter the applied voltage, or clear that field for a resistance-only sum.
- Read the total and inspect the component table for the individual voltage drops.
Formula
Rtotal = R1 + R2 + …; I = V/Rtotal; Vk = I × Rk; Pk = Vk × I
A series connection has the same current through every component because there is no branch between them. Voltages across the resistors add to the applied voltage. Zero-valued resistors can be included, but a voltage-to-current calculation needs positive total resistance.
Example
Resistors of 100 Ω, 220 Ω and 330 Ω sum to 650 Ω. Applying 13 V gives a current of 0.02 A. The voltage drops are 2 V, 4.4 V and 6.6 V, which add to 13 V. Their total dissipated power is 0.26 W.
Frequently asked questions
Does resistor order change the total?
No. Rearranging ideal series resistors leaves their sum and the circuit current unchanged. The potential of each intermediate junction can change.
Can I mix ohms and kilohms in one list?
Convert them into the single selected unit first. Text suffixes are rejected so that a partially parsed entry cannot silently change the circuit.
What does clearing the voltage do?
It returns only the equivalent resistance and component values. No current or power is inferred without an applied voltage.
Does this cover every resistor network?
No. Branches create parallel paths and require a different reduction. Real component ratings, tolerances and self-heating also need information beyond the nominal values entered here.
Sources
Last updated: 2026-10-30