Enter up to 8 resistor values (in Ohms, Kilohms, or Megohms) to calculate the total series resistance. Add as many resistors as your circuit needs — the Series Resistor Calculator sums them using the formula RTotal = R1 + R2 + … + Rn and displays your result in Ω, kΩ, and MΩ.
Total Series Resistance
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Total Resistance (kΩ)
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Total Resistance (MΩ)
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Number of Resistors
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The total resistance of resistors connected in series is simply the sum of all individual resistances: R_Total = R1 + R2 + R3 + … + Rn. Because the same current flows through every component in a series circuit, resistances add directly — unlike in parallel circuits.
In a series connection, every additional resistor forces current to pass through it, creating more opposition to current flow. Each resistor adds its full value to the total, so the equivalent resistance can never be less than the largest individual resistor in the string.
Yes. This calculator lets you select the unit (Ω, kΩ, or MΩ) for each resistor independently. All values are internally converted to Ohms before summing, and the result is displayed in all three units for convenience.
In a series circuit, resistors are connected end-to-end so the same current passes through all of them, and total resistance equals the sum of all values. In a parallel circuit, resistors share the same voltage across their terminals, and total resistance is always less than the smallest individual resistor. Use 1/R_Total = 1/R1 + 1/R2 + … for parallel configurations.
This calculator supports up to 8 resistors in a single calculation. Only filled-in fields are included in the sum — leave optional fields blank if you have fewer than 8 resistors in your circuit.
No. Current remains constant throughout a series circuit — the same amount of current flows through every resistor. What changes across each resistor is the voltage drop, which is proportional to each resistor's individual value (V = I × R).
You can use Ohm's Law: R = V / I, where V is the total voltage across the circuit (in volts) and I is the current (in amperes). This gives you the equivalent total resistance directly without needing to know individual resistor values.
Series resistors are used in LED current-limiting circuits, voltage dividers, pull-up/pull-down networks, filter design, and signal attenuation. Anytime you need to increase the total impedance in a circuit path or distribute voltage drops across components, a series configuration is the go-to approach.