Electronics Tools
Free calculators for circuit design and component selection. Use these tools while building Arduino projects or designing circuits. Learn the theory behind these calculations in our learning center.
Band decoder
Resistor Color Code Calculator
Decode 4, 5, and 6-band resistors, reverse-map target values, and compare against E-series stock values.
V I R P
Ohm's Law Calculator
Solve voltage, current, resistance, and power with unit conversion plus practical heat guidance.
R1 R2 load
Voltage Divider Solver
Calculate ideal output, loaded output, R1, R2, load error, divider current, and output impedance.
Current limit
LED Series Resistor Calculator
Find current-limiting resistance, nearest E12 value, wattage margin, and voltage headroom.
τ = R × C
Capacitor Charge / Discharge
Calculate RC time constant τ, full-charge time (5τ), voltage at any time point, and RC filter cutoff frequency.