TOOLSElectronics calculators.
Free calculators for hardware builders. Each one is worked from a real OTD board, with the formula and a cited source.
- CalculatorLiPo battery runtime calculator (ESP32 / microcontroller)Estimate runtime from battery capacity, average current draw, and usable capacity. Worked from a real ESP32-S3 board's measured budget.
- CalculatorWS2812 / NeoPixel power supply calculatorSize a 5 V supply for an addressable LED string from pixel count, per-pixel draw, and headroom. Grounded in the WS2812B datasheet figure.
- CalculatorOhm's law calculator (V, I, R, and power)Solve Ohm's law for voltage, current, or resistance, and get the power. Enter any two of V, I, R. Worked from a real ESP32 board's indicator LED.
- CalculatorLED series resistor calculator (Ω from supply, Vf, current)Size an LED's current-limiting resistor from supply voltage, forward voltage, and target current. Gives the nearest E24 standard value and the power it burns.
- CalculatorVoltage divider calculator (Vout, R1, R2)Compute a resistive divider's output voltage and quiescent current from Vin, R1, and R2. Sized for fitting a higher voltage into an ESP32's 3.3 V ADC.
- CalculatorLDO headroom + dissipation calculator (linear regulator)Check a linear regulator's headroom against its dropout and find the power it dissipates as heat, from Vin, Vout, dropout, and load current.
- CalculatorRC filter cutoff frequency calculator (first-order)Find a first-order RC filter's −3 dB cutoff (fc = 1 / 2πRC) and time constant from R and C. For ADC anti-alias and noise filtering.
- CalculatorPCB trace width calculator (IPC-2221)Find the minimum trace width for a current at a chosen temperature rise (IPC-2221), for external or internal copper. Grounded in a real high-current board.
- CalculatorResistor power dissipation calculator (wattage rating)Find the power a resistor dissipates (P = I²R) and the smallest standard wattage rating with a 2x margin, from its current and resistance.
- CalculatorBattery watt-hours calculator (mAh to Wh, pack sizing)Convert cell capacity and voltage to watt-hours and size a series/parallel pack's energy, voltage, and capacity. mAh to Wh done right.