True Random Numbers vs ResiCalc

Most random number generators calculate the numbers with pseudo random number generators. But this app leverages your device's motion sensors, swipes, or camera input, to generate authentically random numbers and shuffles. It also doesn't have a modulo bias, a common problem with random number generators.

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.