Series and Parallel Resistance Calculator

This calculator finds the total, or equivalent, resistance of a group of resistors connected either in series or in parallel, working out both at once from a single list of values. Combining resistors is one of the first things you learn in circuit analysis, and the two arrangements behave very differently. In series, where resistors are joined end to end so the same current flows through each, the resistances simply add up, and the total is always larger than any single resistor. In parallel, where resistors share the same two connection points so the current splits between them, you add the reciprocals of the values and take the reciprocal of that sum, and the total is always smaller than the smallest resistor in the group. You enter your resistor values separated by commas, spaces or new lines, all in the same unit such as ohms, and the calculator returns the series total and the parallel total side by side, along with the count of resistors. This is exactly what you need when designing a circuit, replacing a hard-to-find value with a combination of common ones, or checking a network on a breadboard. Keep every value in the same unit to get a correct answer. Enter your resistors to see both totals straight away.

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