ESP32 Calcs

Electronics Calculators — Battery, LED, Divider, PCB Trace, LED Strip

The five calculations every microcontroller project runs into — battery runtime, LED resistors, voltage dividers, PCB trace widths and LED strip power — with the practical traps (Wi-Fi vs ADC2, GPIO current limits, power injection) baked into each answer.

The tools

Battery Life CalculatorBattery runtime for microcontroller projects: enter capacity, active current, duty cycle and sleep current to get real-world battery life in hours and days — the way it actually behaves on an ESP32-class board.LED Resistor CalculatorSeries resistor for one or more LEDs: enter supply, forward voltage and target current to get the exact resistance, the nearest E24 value to buy, actual current and the power rating you need.Voltage Divider CalculatorTwo-resistor voltage divider: output voltage, divider current and dissipation — plus the R2 value that hits a target voltage, and the ESP32 ADC limits that decide whether your reading will actually be stable.PCB Trace Width CalculatorIPC-2221 trace width for your current, temperature rise and copper weight — external or internal layer — plus resistance and voltage drop when you enter the trace length.LED Strip Power CalculatorPower supply sizing for LED strips: enter length and W/m to get total watts, total amps, the PSU wattage to buy with headroom, and how many power injection points the strip needs.

Calculators that say what to do, not just what the number is

A resistor value by itself is useless if it's not a value you can buy, or if the resistor will cook at the power it dissipates. Each calculator here converts the raw formula into a procurement decision: the E24 resistor to order, the standard power rating to buy, the PSU wattage with headroom, the trace width to actually route. Every formula is a pure function with unit tests in the repo — battery runtime uses weighted duty-cycle current, LED resistors use the classic series formula with E24 rounding, PCB traces follow the IPC-2221 chart formula for external and internal layers.

Built for the 3.3 V world

Most online calculators assume 5 V Arduino logic; these are tuned for the ESP32 reality of 3.3 V GPIOs, 12-bit ADCs with attenuation quirks, and an input range that does not tolerate 5 V. Where a calculation has a microcontroller-specific trap — ADC2 dying under Wi-Fi, GPIO current limits when driving an indicator LED, why a 5 V LED strip needs a level shifter on the data line — the answer text calls it out next to the number.

Guides that use these tools