ResiCalc: Resistor Networks

ResiCalc turns any resistor network into a clear answer — and shows you exactly how it got there.

From high-school series/parallel problems to Wheatstone bridges and Y–Δ transforms in circuit theory, to voltage dividers and power checks at the bench, ResiCalc solves it and explains it.

DRAW IT, SOLVE IT
• Tap to place nodes, drag to connect resistors; 0 Ω is an ideal wire
• Grid snapping, undo/redo, pinch to zoom and pan
• Pick any two nodes as terminals — the equivalent resistance updates live
• IEC rectangle or ANSI zig-zag resistor symbols

STEP-BY-STEP SOLUTIONS
• Merges wires, removes dangling and floating branches, combines series and parallel
• Detects balanced bridges; otherwise applies Y–Δ (star–mesh) transforms
• Every step comes with an explanation, the worked formula and a diagram
• Great for homework checks, exam revision and teaching

FULL CIRCUIT ANALYSIS
• Apply a voltage or current source across the terminals
• Node voltages plus voltage, current, power and load ratio for every resistor
• Current arrows, node voltages and a power heat map directly on the canvas
• Set power ratings and get overload warnings

ENGINEERING-GRADE TOLERANCE
• Exact worst-case bounds
• Monte Carlo histogram and yield
• Sensitivity ranking shows which resistor deserves a precision part

RESISTOR TOOLBOX
• 4/5/6-band color code, both directions
• E3–E192 standard values
• Combination finder: hit any value with 2–3 standard resistors
• Voltage divider designer
• Ohm's law and quick series/parallel calculators

MORE
• Multiple projects and 11 classic templates (resistor cube, R-2R ladder, 3×3 grid…)
• Export PNG schematics and multi-page PDF reports
• English and Chinese, Dark Mode
• Fully offline, no data collection, no ads

FREE AND PRO
Drawing circuits, equivalent resistance, templates and the core tools are free.
ResiCalc Pro is a one-time purchase (no subscription) that unlocks full analysis, all solution steps, tolerance analysis, the combination finder, divider designer, unlimited projects and PDF reports.