Circuit Calculator
Series & parallel resistors, voltage dividers, and LED resistor sizing — with auto-generated circuit diagrams.
Series Resistors — Rtotal = R₁ + R₂ + … + Rn
V
Parallel Resistors — 1/Rtotal = 1/R₁ + 1/R₂ + … + 1/Rn
V
Voltage Divider — Vout = Vin × R₂ / (R₁ + R₂)
Input Voltage Vin (V)
R₁ (Ω)
R₂ (Ω)
Desired Vout (V) — optional
LED Series Resistor — R = (Vsupply − Vf) / If
Supply Voltage Vs (V)
LED Current If (mA)
LED Forward Voltage Vf (V)