Series and parallel resistance calculator
Combine resistors, capacitors or inductors in series, parallel or mixed networks and see the working.
Series and parallel resistance calculator
Paste a list of resistor values — one per line or comma-separated — and this tool adds them in series, combines them in parallel, or works out a mixed network written with parentheses, showing the formula alongside the result. It reads any common notation: a plain number like 4700, a decimal with an SI suffix like 4.7k, or the shorthand that uses the suffix letter as the decimal point, like 4k7 or 2R2, so you can paste straight from a datasheet without reformatting.
Component switches the formula: resistors and inductors add in series and use the reciprocal-of-reciprocals rule in parallel, while capacitors use the opposite pairing, so the same list gives a different result depending on which part you're combining. Connection chooses series, parallel, or mixed — for a mixed network, wrap any sub-group that combines the other way in parentheses, such as "100, (220, 330)" for a 100 Ω resistor in series with a 220 Ω and 330 Ω pair in parallel; groups can nest. Turn on "Solve for a missing value" to work backwards: mark the unknown with a question mark in a plain series or parallel list, give the target result, and the tool computes what that value has to be. Round to the nearest standard E12 or E24 value when you need a part you can buy, and set how many significant digits results carry.
Large or small results show with the matching SI prefix — p, n, µ, m, k, M, G — instead of a long string of zeros, and a network that can't be evaluated, such as an unbalanced bracket or an unreachable target, gets a plain-language error explaining what to fix.
Everything runs locally in your browser: the network you're designing is never sent anywhere. Copy the result, download it as a .txt file, or send it straight into another tool's input to keep working.