Resistors in Series Calculator

When resistors are connected end-to-end in a circuit (in series), their resistances add together — and the Resistors in Series Calculator works out the combined total for you. Select the number of resistors (up to 10) and your resistance unit (Ω, kΩ, or MΩ), then enter values for R1 through R10 to get the Total Series Resistance, along with the largest resistor's percentage contribution to the total.

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Total Series Resistance

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Largest Resistor Contribution

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Current Through Circuit

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Frequently Asked Questions

How do I calculate the equivalent series resistance?

For resistors in series, the total resistance is simply the sum of all individual resistances: R_total = R1 + R2 + R3 + ... + Rn. This is because current flows through each resistor sequentially, and each resistor adds its resistance value to the total.

What is the equivalent resistance of resistors with 1.5 kΩ, 300 Ω, and 0.7 kΩ?

To find the total: 1.5 kΩ + 0.3 kΩ + 0.7 kΩ = 2.5 kΩ. Remember to convert all values to the same unit before adding. In this case, 300 Ω = 0.3 kΩ.

Why do we sum the resistances of resistors in series?

In a series circuit, current must flow through each resistor one after another. Each resistor opposes the current flow, so the total opposition (resistance) is the sum of all individual resistances. Think of it like obstacles in a single-lane road - each one adds to the total difficulty.

Is resistance higher in series or in parallel?

Resistance is always higher in series than in parallel. Series resistance equals the sum of individual resistances, while parallel resistance is always less than the smallest individual resistor in the circuit.

What happens to current in a series circuit?

In a series circuit, the same current flows through all components. The current is determined by the total voltage divided by the total resistance (I = V/R_total). This current remains constant throughout the entire series path.

How do voltage drops work in series circuits?

In series circuits, voltage drops across each resistor add up to the total supply voltage. Each resistor's voltage drop is proportional to its resistance value: V_resistor = I × R_resistor, where I is the constant current through the circuit.

Can I mix different types of resistors in series?

Yes, you can connect different types of resistors (carbon, metal film, wire-wound, etc.) in series as long as their power ratings are adequate. The calculation method remains the same - just add up all the resistance values regardless of resistor type.