Power Electronics Calculators
20 free calculators with formulas and worked examples.
Buck, boost, and flyback converter design, LDO dropout, MOSFET power dissipation, battery life, PWM duty cycle, and power factor calculators for power supply design.
Voltage Divider
Calculate voltage divider output voltage, current, Thévenin impedance, and power dissipation from Vin, R1, and R2. Ideal for bias networks and level shifting.
LED Resistor
Calculate the correct current limiting resistor for an LED. Shows exact value, nearest E24 standard, actual current, and power dissipation.
Buck Converter
Design a synchronous buck (step-down) converter: calculate duty cycle, inductor value, output capacitor, and input capacitor.
LDO Thermal
Calculate LDO regulator power dissipation, junction temperature, thermal margin, and minimum dropout voltage for thermal design validation.
Battery Life
Estimate battery runtime for IoT and portable devices given average current draw, duty cycle, self-discharge rate, and depth-of-discharge cutoff. Suitable for LiPo, alkaline, NiMH, and coin-cell batteries.
Power Factor
Calculate power factor, reactive power, and correction capacitor for AC circuits
Boost Converter
Calculate duty cycle, inductor value, and output capacitor for boost (step-up) DC-DC converter design
3-Phase Power
Calculate three-phase real power, reactive power, apparent power, current, and power factor from line or phase values
PWM Duty Cycle
Calculate PWM duty cycle, frequency, average voltage, off-time, and RMS voltage from on-time and period parameters
MOSFET Power Loss
Calculate MOSFET conduction loss, switching loss, total power dissipation, junction temperature, and efficiency for power electronics design
Solar Panel Sizing
Calculate solar panel wattage, battery capacity, and charge controller current for off-grid photovoltaic systems based on load and sun hours
Battery Charge Time
Calculate Li-ion battery charge time using CC/CV method, including CC phase duration, total charge time, energy input, and charging efficiency
Inrush Current Limiter
Calculate NTC thermistor requirements for inrush current limiting, including cold resistance, peak inrush current, time constant, and energy absorbed
Charge Pump
Calculate Dickson charge pump output voltage, loaded voltage, output ripple, and efficiency for switched-capacitor voltage multiplier circuits
Switching Regulator Ripple
Calculate buck converter output voltage ripple, inductor current ripple, and ESR contribution for switching regulator design
LDO Dropout
Calculate LDO regulator power dissipation, junction temperature rise, minimum input voltage, efficiency, and headroom for linear regulator design
Transformer Turns Ratio
Calculate transformer turns ratio, secondary current, apparent power, and real power delivered. Accounts for transformer efficiency.
Flyback Converter
Calculate flyback converter turns ratio, peak primary and secondary currents, and power levels for isolated DC-DC converter design.
Supercap Backup
Calculate supercapacitor backup time, stored energy, and charge time for power backup applications using ultracapacitors.
Battery Internal Resistance
Calculate battery internal resistance from open-circuit and loaded voltage measurements, determine power loss and maximum short-circuit current.
About Power Electronics Calculators
Power electronics converts electrical energy between forms — AC to DC, high voltage to low voltage, variable to regulated — with the highest possible efficiency. Where analog electronics minimizes dissipation by operating transistors in linear regions, power electronics embraces switching: transistors spend most of their time fully on or fully off, dissipating power only during transitions.
The buck converter is the workhorse of modern electronics. It steps down voltage by switching a transistor at tens to hundreds of kilohertz, storing energy in an inductor during the on-phase and releasing it through a diode (or synchronous rectifier) during the off-phase. The duty cycle — fraction of time the switch is on — equals V_out / V_in in continuous conduction mode. Inductor and output capacitor sizing determines ripple current and output voltage ripple.
LDO linear regulators sacrifice efficiency (dissipating V_in − V_out as heat) for simplicity and low noise — essential for sensitive analog and RF circuits where switcher noise would be unacceptable. MOSFET power dissipation calculators determine heatsink requirements. Battery life projectors translate average current draw into runtime, accounting for discharge curves and temperature derating.
SMPS control loop stability is the advanced topic: a compensated error amplifier must provide enough phase margin (typically >45°) across the closed-loop bandwidth while rejecting supply disturbances. The async simulation tool on this site generates Bode plots and Monte Carlo yield analysis for complete SMPS designs.