Example 1
Cz = 3 µF.
Parallel capacitance calculator
Type C1 [F] and C2 [F]. The calculator computes Cz = C1+C2: 1 µF and 2 µF is 3 µF, and two 10 µF capacitors are 20 µF. In parallel the voltage is the same and charges add.
Series: 1/Cz = 1/C1+1/C2. One C: C = Q/U.
Result
Capacitance C₁ (F) and Capacitance C₂ (F). The result shows up here.
How it works
Parallel equivalent capacitance is a sum: Cz = C1 + C2. At 1 µF and 2 µF you get 3 µF. At two 10 µF you get 20 µF. At 100 nF and 470 nF you get 570 nF. Parallel Cz grows, like resistors in series. Voltage on both is the same, charges Q1 + Q2 = Qz.
The form has two fields: C1 and C2 in farads. 1 µF = 1e-6. The result is in F. Type 1e-6 and 2e-6, not 1 and 2, if you mean microfarads. A comma and 1e-6 mean the same C.
Typed 0 in one field makes Cz equal the other: zero farads adds nothing. Both fields need a number before 3 µF appears. In parallel C = Q/U grows, because Qz is larger at the same U.
In series Cz drops: 1/Cz = 1/C1 + 1/C2. Here a sum. C = Q/U is one capacitor. Energy E = ½ C U² already takes one C, for example this Cz.
Three capacitors take two steps: first Cz from a pair, then that Cz plus C3. The calculator has two fields and stops at farads, not joules.
Type 1e-6 and 2e-6, click Calculate, and check 3 µF. Two 10 µF (1e-5) give 20 µF. The calculator adds two numbers; it does not guess ESR.
How to use
- In the first field enter C1 in farads, for example 1e-6. 1 µF is 1e-6, not 1.
- In the second field enter C2 in farads, for example 2e-6.
- Click Calculate. The calculator adds C1 and C2. 1 µF and 2 µF give 3 µF. Two 10 µF give 20 µF.
- Typed 0 adds 0, so Cz equals the other. Both fields need a number.
- For series 1/Cz, open series capacitance. One C is on C = Q/U.
Formula
Cz = C1 + C2
C1, C2 >= 0.
Sum of parallel capacitances
In parallel the plates add: Cz = C1+C2. 1 µF and 2 µF is 3 µF. Two 10 µF capacitors are 20 µF. Shared voltage, charges add.
- Cz
- The sum C1+C2 [F]. Larger than each part. Not the series reciprocal.
- C1
- First branch [F], for example 1e-6. Charge on it is C1·U.
- C2
- Second branch [F]. 2 µF next to 1 µF gives Cz = 3 µF.
Real-life examples
Example 2
Cz = 20 µF.
Example 3
Cz = 570 nF.
Example 4
C<sub>1</sub> = 5 µF, C<sub>2</sub> = 0 -> Cz = 5 µF.
Example 5
22 nF + 33 nF.
Example 6
1000 µF + 2200 µF.
Example 7
4.7 µF + 4.7 µF = 9.4 µF.
Example 8
C<sub>1</sub> = 1 µF, C<sub>2</sub> grows: linear chart.
Example 9
Two electrolytics in parallel.
Example 10
Parallel: larger Cz than series.
Ways to use this calculator
- You add 1 µF and 2 µF to 3 µF.
- You check two 10 µF: 20 µF.
Frequently asked questions
How much Cz at 1 µF and 2 µF in parallel?
Equivalent capacitance is 3 µF. You add 1e-6 and 2e-6. Type farads, not the bare 1 and 2.
How much with two 10 µF?
You get 20 µF. Two equal capacitors in parallel double the capacitance; they do not halve it.
Which units do I type?
Both capacitances C1 [F] and C2 [F]. Result Cz [F]. 1 µF = 1e-6 F, 100 nF = 1e-7 F.
How is this different from series?
In parallel Cz is a sum, so larger than each branch. Series uses 1/Cz = 1/C1 + 1/C2 and Cz comes out smaller.
Is the voltage the same?
Yes. In parallel both plates sit on the same U [V]. Charges Q = C U add, which is why the C values add.
Does a comma in 0.000001 work?
Yes. 0.000001, 0,000001 and 1e-6 are the same C [F]. 1e-6 is easier.
Where is C = Q/U?
On the capacitance-from-charge page. Here you already add two C values; you do not solve one C from Q.
Where is energy?
On the capacitor-energy page. There E = ½ C U². Here you only add two capacitances.
What if one C is 0?
Cz equals the other branch. Zero farads add nothing. Both fields still need a number.
How much at 100 nF and 470 nF?
You get 570 nF. 1e-7 plus 4.7e-7. That is a sum, not the series reciprocal.
Knowledge sources
The formula is the school one. Units follow SI; NIST SP 330 and BIPM define the measures, not your result.
Page updated in 2026.