# Resistor Series / Parallel Calculator Combine resistors in series, parallel, or an arbitrary +/| expression, with per-resistor voltage and power > Canonical page: https://elysiatools.com/en/tools/resistor-series-parallel-calculator - **Category:** Math & Numbers - **Keywords:** resistor, series, parallel, equivalent resistance, combine resistors, electronics, circuit, resistance network, expression ## Overview Combine a list of resistors into one equivalent resistance. Modes: - Series: R = R1 + R2 + … - Parallel: 1/R = 1/R1 + 1/R2 + … - Expression: + for series, | for parallel, with parentheses. e.g. (10|10)+20 = 10∥10 then +20 in series = 25Ω. Value suffixes: k/K, M, m, u/µ. With an optional voltage, total current and per-resistor power are reported. ## Inputs - **Calculation Mode** (select) - **Resistance Values (one per line, or comma-separated)** (textarea): e.g. 1000 2200 4700 or in expr mode: (10k|10k)+470 - **Applied Voltage (V, optional)** (number): e.g. 12 — leave blank to skip power calc ## When to use - When designing or prototyping electronic circuits and needing to find the equivalent resistance of a network. - When substituting a missing resistor value by combining available resistors in series or parallel. - When calculating power dissipation and voltage drops across individual resistors in a network under a specific applied voltage. ## How it works - Select the calculation mode: Series, Parallel, or Expression. - Enter the resistor values separated by lines or commas, using standard unit suffixes like k, M, m, or u. - Optionally enter the applied voltage to calculate the total current and per-resistor power distribution. - Click calculate to view the equivalent resistance and the detailed electrical breakdown. ## Use cases - Finding the equivalent resistance of a complex network using custom expressions like (10k|10k)+470. - Determining if a specific resistor combination will exceed the power rating of individual components under a given voltage. - Prototyping breadboard circuits when the exact required resistor value is not available in your inventory. ## Frequently asked questions ### What operators are supported in Expression mode? Use '+' for series connections and '|' for parallel connections, along with parentheses to define the order of operations. ### Which unit suffixes can I use for resistor values? You can use standard suffixes like k or K (kiloohms), M (megaohms), m (milliohms), and u or µ (microohms). ### How do I calculate the power dissipation for each resistor? Enter a value in the Applied Voltage field, and the calculator will automatically compute the current and power for each resistor. ### Can I mix different unit suffixes in the same calculation? Yes, the calculator automatically normalizes values like 10k, 470, and 2.2M to ohms before performing the calculation. ### What formula is used for parallel resistance? 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