How this calculator works
An unloaded divider follows the complex impedance ratio of its lower element to the sum. Resistive and same-type reactive dividers have a real ratio. Mixed RC and RL dividers change both magnitude and phase with frequency. Capacitive division is inverse in capacitance because capacitive impedance is inversely proportional to C. Load impedance, source impedance and inductor coupling are omitted, so attaching a significant load changes the result.
Formula
H = Z2/(Z1+Z2); Vout = Vin |H|; phase = arg(H). ZR = R; ZC = -j/(2 pi f C); ZL = j 2 pi f L.
Worked example
A 12 V input with R1 = 1000 ohm and R2 = 2000 ohm gives 8 V across R2. Capacitors C1 = 1 microfarad and C2 = 2 microfarads give 4 V across C2 in ideal AC steady state.
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Frequently asked questions
Which component is the output across?
The second or lower element, connected between the output node and return.
Can I use a capacitor divider at DC?
The impedance ratio describes AC steady state. DC capacitor voltages depend on initial charge and leakage.
Why is there a phase shift?
Reactive voltage and current are not in phase, so a mixed impedance ratio is complex.