# Why should I put capacitors in parallel?

May 18, 2015

Actually, there is no right or wrong answer here. Capacitors can be connected in series or parallel. The choice depends on what the circuit needs to accomplish. It may also depend on the specifications of the capacitors.

Connecting two capacitors in parallel results in a capacitance that is the sum of the capacitance of each.

$C = {C}_{1} + {C}_{2}$

Connecting two capacitors in series requires a little more math.

$C = \frac{1}{\frac{1}{C} _ 1 + \frac{1}{C} _ 2}$

Now let's look at how that math works out if we choose a value of 5 for both ${C}_{1}$ and ${C}_{2}$.

Parallel: $C = 5 + 5 = 10$
Series: $C = \frac{1}{\frac{1}{5} + \frac{1}{5}} = \frac{1}{\frac{2}{5}} = \frac{5}{2} = 2.5$

Why would you want each of these circuits?
If the total capacitance required were 2.5 or 10, the choice is clear.

But it might also be the case that your circuit runs at 100 Volts and these components are only capable of operating at 60 Volts. Two capacitors in series would allow you to connect across a 120 Volt connection.