Led Resistor Pro

A practical tool for electronics hobbyists, students, and makers who work with LEDs. CALCULATORS • Single LED — enter supply voltage and forward current, get the exact resistor value snapped to E24/E12 series with 4-band and 5-band colour codes. • Series string — calculates the single dropping resistor for any number of LEDs in series. • Parallel array — per-LED or shared resistor mode, shows per-branch and total current. • Matrix (series-parallel) — handles multi-string arrays with a resistor per string. • RGB LED — independent resistor for each channel (R/G/B), common-cathode or common-anode, with a live colour preview. CIRCUIT VIEWS Every calculator shows an animated circuit diagram that responds to your inputs — LED brightness scales with forward current, particles flow along the wires. LED LIBRARY 109 LEDs across 26 categories: standard 3/5/8/10 mm, high-brightness, high-power (1 W – 10 W), SMD (0402 to 5730), COB modules, RGB, bicolour, IR, UV, flashing, 7-segment, and LED strips (12 V and WS2812). Tap any LED to view its full datasheet and open it directly in the calculator. GRAPHS Interactive I–V curves (Shockley model), resistor value vs supply voltage, and resistor/LED power vs current — pinch to zoom, drag to pan. LEARN Ten built-in lessons covering LED basics, forward voltage, resistor selection, colour codes, series/parallel wiring, RGB LEDs, high-power LEDs, and strips. No ads. No internet required. Works fully offline.