Resistora

Resistor Tools

Professional calculators and circuit design tools for electrical engineering

Resistor Combination Finder

Find the best resistor combinations to achieve your target resistance. Search through your available resistors and get optimized circuit solutions.

Circuit Calculator

Build custom resistor circuits with up to 10 different schemas. Input resistance values and calculate total circuit resistance instantly.

Series/Parallel Calculator

Calculate total resistance for series or parallel resistor circuits. Add multiple resistors with optional tolerance, voltage, and power ratings.

Voltage Divider

Design voltage divider circuits to step down voltage levels. Input your source voltage and target voltage to find optimal resistor configurations.

E-Series Resistor Finder

Find resistor combinations from standard E-series (E6–E192) to match a target resistance. Select your preferred E-series and get optimized circuit solutions.