All Tools

Calculate capacitance, charge, energy, and reactance for capacitors, plus series and parallel combinations. SI unit prefixes with real-time results and formulas.

Calculate inductance, stored energy, inductive reactance, series/parallel combinations, and LC resonant frequency with quality factor.

Find the right wire gauge for your circuit from current, voltage, run length, and acceptable voltage drop, with AWG and mm² results.

Calculate output voltage for a two-resistor voltage divider, find the resistor needed for a target voltage with E24 suggestions, and analyze load effects.

Calculate Voltage, Current, Resistance, and Power instantly. Enter any 2 values and get the other 2 using Ohm's Law and the Power Wheel.

Decode resistor values from color bands (4, 5, 6-band) or convert resistance values back to color codes instantly.

Estimate how long a battery will last from its capacity, current draw, and circuit efficiency, or find the capacity you need for a target runtime.

Play piano in your browser with realistic sounds, four instruments, recording with MP3 export, a song library with learn mode, and a metronome.

Find the right current-limiting resistor for your LED circuit, with the nearest E24 value, color code, power rating, and a live diagram for single, series, or parallel LEDs.

Practice music with a precise online metronome. Set the BPM, choose a time signature, build accent patterns, add subdivisions, and pick from multiple click sounds.

Make beats with an online drum machine: a 16-step sequencer, 808 and Acoustic kits, swing, presets, and WAV export.

Build any musical scale, see its notes on piano and guitar fretboard, hear them play, view intervals and diatonic chords, and compare scales side by side.