Resistor Parallel & Series Calculator

This calculator finds the total resistance of a group of resistors, both when they are wired in series and when they are wired in parallel, from a list of their values. Combining resistors is one of the most basic and frequent tasks in electronics, and the two arrangements behave very differently. In series, resistors are connected end to end so the same current flows through each, and their resistances simply add up, giving a total larger than any single one. In parallel, resistors are connected across the same two points so they share the current, and the total resistance is always less than the smallest individual resistor, because the extra paths make it easier for current to flow. The parallel calculation is the one people find fiddly, since it works through the reciprocals of the resistances. This tool handles both at once. You paste or type your resistor values in ohms, and the calculator returns the series total, the sum of them all, and the parallel total, computed from the reciprocals, along with the number of resistors. The results update as you type, so you can add or change values and see both totals instantly. Use it to design and analyse circuits, to find a combination that gives a target resistance, or for electronics study and homework. A handy fact the calculator illustrates: two equal resistors in parallel give exactly half their value, and the parallel total can never exceed the smallest resistor in the group. Series and parallel combinations are the foundation for understanding more complex networks, which can often be reduced step by step to a single equivalent resistance using exactly these two rules.

Series: resistances add. Parallel: 1/total = sum of 1/R. The parallel total is always less than the smallest resistor. Values in ohms.