Tools that pull their weight
Calculators
Interactive design calculators for the bench — free, fast, and built to be trusted. Suggestions welcome; this collection keeps growing.
11 of 11 calculators
Core electronics
Voltage divider
Design two-resistor dividers, check load effects, and solve for a target output voltage.
Core electronics
Ohm's law
Solve voltage, current, resistance, and power relationships in resistive circuits.
Core electronics
LED series resistor
Pick the right resistor for LEDs from supply voltage, forward voltage, and current.
Power and battery
Battery life
Estimate battery runtime from capacity, load current, efficiency, and duty cycle.
Timing and oscillators
555 timer
Calculate astable frequency, duty cycle, and monostable pulse width.
Timing and oscillators
Crystal load capacitor
Calculate matching load capacitors for crystals and simple oscillator circuits.
Signals and RF
Op amp gain
Calculate inverting, non-inverting, and simple differential gain from resistor values.
Signals and RF
RMS and peak voltage
Convert between RMS, peak, peak-to-peak, and average rectified waveform voltage.
Passives
Resistor value decoder
Decode colour bands and SMD resistor markings into resistance values.
Passives
Series and parallel resistors
Calculate equivalent resistance for resistor lists in series and parallel.
Signals and RF
RC and RL filter
Calculate cutoff frequency for simple passive RC and RL low-pass or high-pass filters.