Free tools
Online electronics calculators
Ohm's law, LED resistor, voltage divider, color code, trace width, battery life: instant results you can then verify in the simulator.
- Ohm's Law Calculator (V = I × R)Enter any two of voltage, current and resistance: the third value and the power are computed instantly.
- LED Resistor CalculatorCompute an LED series resistor from supply voltage, forward voltage and target current, rounded to the next standard E12 value.
- Voltage Divider CalculatorGet the output voltage of a two-resistor divider, the current through it and the dissipated power.
- Resistor Color Code Calculator (4-band)Pick the four band colors to read the resistor's value and tolerance.
- PCB Trace Width Calculator (IPC-2221)Compute the minimum trace width from current, temperature rise and copper thickness (IPC-2221).
- Battery Life CalculatorEstimate the runtime of an Arduino, ESP32 or sensor project from capacity (mAh) and average current, sleep mode included.