Capacitors in Series Calculator
Total series capacitance, charge, energy and voltage on each capacitor.
What it does
Capacitors in series hold the same charge. The total capacitance is smaller than the smallest one, and the voltage splits in inverse proportion to capacitance.
Where it's used
Raising the voltage rating of a capacitor bank and building capacitive dividers.
How to use it
- Type the values separated by commas, e.g.
100n, 220n. - Enter the applied voltage.
- Optional: set a frequency to see the reactance.
- Check the voltage on each capacitor against its rating.
The formula explained
- 1/C_total
- 1/C1 + 1/C2 + … + 1/Cn
- Q
- C_total × V — the same charge on every capacitor
- V_n
- Q / C_n — voltage on capacitor n
- E
- ½CV², energy stored
- X_C
- 1 / (2πfC), opposition to AC
Worked example
100 nF and 220 nF in series across 50 V.
Inputs:
- Capacitor values (comma separated): 100n, 220n F
- Applied voltage: 50 V
- Frequency (reactance): 50 Hz
The calculator gives:
- Total capacitance: 68.75 nF
- Total charge Q: 3.438 µC
- Stored energy: 85.94 µJ
Tips and common mistakes
- The smallest capacitor takes the largest voltage — check its rating.
- Electrolytics in series need a balancing resistor across each one because their leakage differs.
- Two equal capacitors in series give half the value.
Questions people ask
What is the formula for two capacitors in series?
Product over sum, just like resistors in parallel: C = C1 × C2 / (C1 + C2). 100 nF and 220 nF in series give 68.75 nF.
How does the voltage split between series capacitors?
Each capacitor holds the same charge Q, so V_n = Q / C_n — the smaller capacitor takes the larger voltage. With 100 nF and 220 nF on 50 V, the 100 nF part sees about 34.4 V and the 220 nF part about 15.6 V.
Why connect capacitors in series at all?
To build a higher voltage rating out of lower-rated parts, or to make a value you don’t have. Two equal electrolytics connected back to back (minus to minus) also make a non-polarised capacitor of half the value.
Related Reactive & RLC calculators
- Capacitors in Parallel
- Inductors in Series
- Inductors in Parallel
- RLC Resonant Frequency
- RLC Parallel Resonance
- RC Time Constant
- Capacitor Reactance
Enter your values to get the result with the formula, substituted values and an explanation of each step.