Electrical & Engineering Calculators

Practical electronics and engineering math: solve Ohm's law, decode resistor color bands, size an LED's series resistor, check voltage drop over a cable run, plan a solar array and battery bank, and work out gear ratios. Educational tools — for mains wiring and high-power installations, always confirm with a qualified electrician and local code.

Ohm's Law CalculatorEnter any two of V, I, R, P — get the other two. Resistor Color Code CalculatorResistor color bands → resistance and tolerance. Wire Gauge CalculatorAWG ↔ mm², with a current-capacity guide. Voltage Drop CalculatorVoltage lost over a cable run, with % check. Power Consumption CalculatorWatts + hours → kWh per day/month/year and cost. LED Resistor CalculatorSeries resistor value and wattage for any LED. Solar Panel Sizing CalculatorSolar array size (kW) and panel count from usage. Battery Life CalculatorBattery runtime from capacity and current draw. Gear Ratio CalculatorGear ratio, output speed and torque from teeth counts.