Free electronics calculators
The sums you reach for at the bench, worked out for you, each with the formula behind it and a free lesson where you build the circuit yourself.
Electronics
- Ohm's law calculatorAny two of V, I and R give the third, and the power.
- Electrical power calculatorWatts from any two of V, I and R, and the resistor rating that stays cool.
- LED resistor calculatorThe resistor for one LED or a string, rounded to a value you can buy.
- Resistor colour code calculatorBands to ohms, or ohms to bands, on 4- and 5-band resistors.
- Resistors in series and parallel calculatorThe total of up to eight resistors, in series or in parallel.
- Voltage divider calculatorVout from two resistors, or the resistor for the Vout you need.
- RC time constant calculatorτ, charge time, cutoff frequency and the voltage at any moment.
- RL time constant calculatorτ, the final current, the rise step by step, and the time to reach a current.
- Capacitive and inductive reactance calculatorA capacitor's or a coil's ohms at any frequency, the current, and the impedance with R.
- RC filter cutoff frequency calculatorThe cutoff from R and C, the part for a cutoff you want, and the gain at any frequency.
- LC resonant frequency calculatorThe frequency an LC circuit rings at, the part that tunes it, and how sharp its peak is.
- Zener diode resistor calculatorThe series resistor for a Zener regulator, and the power ratings it needs.
- Op-amp gain calculatorGain from two resistors, the output peak, and whether it clips at the rails.
PCB Design
Signals & Wireless (RF)
Digital Logic
Power & Energy
- Capacitor energy calculatorJoules and charge in a capacitor, and how much your circuit can use.
- Wire voltage drop calculatorVolts and watts lost in a cable, out and back, and the size that keeps it under 3%.
- Buck converter calculatorDuty cycle, ripple current, output ripple and the coil a step-down converter needs.
- Battery life calculatorHours from mAh and milliamps, for a steady load or a device that sleeps.