Utilities

Resistor Color Code
4/5/6-band

Pick band colors to decode resistance, tolerance, and tempco.
555 Timer Calculator
Astable / Monostable

Enter any three, solve the fourth. Duty, frequency, and component values.
Voltage Divider
With load option

Solve Vin, Vout, R1, R2 (and RL). Currents & power included.
LED Series Resistor
E‑series rounding

Resistor for 1–N LEDs in series, with power rating suggestion.