Resistor & Circuit Tools

Get a resistor substitute or equivalent — enter the resistors you have and a target resistance, and Resistora searches every series, parallel, and mixed combination and returns the closest buildable options, ranked by error.

Find the closest standard E6–E192 resistor equivalent to a target value you can actually buy. Pick a series and combination size and get results ranked by error.

Get a specific output voltage — like 5V from 12V — from a source. Enter your resistors, source voltage, and target, and get the 2- or 3-resistor divider that lands closest.

Already know your resistors and topology? Pick a divider schema, set the values and source voltage, and get the exact output voltage instantly.

Build a resistor network from 16 series/parallel schemas and calculate total resistance, plus combined tolerance, voltage, and power with worst-case min/max bounds.

Quickly calculate the total resistance of resistors in series or parallel, with optional tolerance, voltage, and power ratings.