Electronics calculators that just work
Fast, accurate engineering tools — built by an electronics engineer, free to use, no sign-up.
All calculators
Resistor Color Code Calculator
Decode 4/5/6-band resistors, or find the bands for a value.
LED Series Resistor Calculator
Pick the right resistor for any LED and supply voltage.
Voltage Divider Calculator
Compute output voltage, current and resistor ratios.
PCB Trace Width Calculator (IPC-2221)
Required trace width for a given current and copper weight.
Microstrip Impedance Calculator
Estimate characteristic impedance from your PCB stackup.
LC Filter Cutoff Frequency Calculator
Compute resonance / cutoff for LC, RC and RL filters.
dB ↔ Power / Voltage Converter
Convert between dB, power and voltage ratios.
RC Time Constant Calculator
Time constant and cutoff frequency from R and C.
555 Timer Calculator
Astable frequency, duty cycle and monostable pulse width.
SMD Resistor Code Decoder
Decode 3-digit, 4-digit and EIA-96 SMD resistor codes.