How do I calculate equivalent capacitance for capacitors in series?

For two capacitors in series, use the formula 1/C_total = 1/C1 + 1/C2. For three, add 1/C3. The calculator does this automatically when you enter the capacitance values in farads.

Why is the equivalent capacitance less than the smallest capacitor?

In series, the total capacitance is always less than the smallest individual capacitor because the effective plate separation increases, reducing overall capacitance. This is a key property of series connections.

Can I use this calculator for capacitors with different units like microfarads?

The calculator expects values in farads (F). If your capacitors are in microfarads (µF), convert to farads by dividing by 1,000,000 before entering, or use a unit converter first.

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计算器: Capacitors in Series.

使用计算器: Capacitors in Series，根据输入获得清晰实用的结果。

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输入数值

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02 / 答案

First capacitance

Second capacitance

Third capacitance (optional)

equivalentCapacitanceF

6.66667e-7F

Results update automatically as you type.

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Cite as: Mathify. (n.d.). 计算器: Capacitors in Series. https://mathify.one/zh/physics/capacitors-in-series

Use Cases

Designing series capacitor circuits

When you need to combine capacitors in series to achieve a specific total capacitance, this calculator helps you quickly find the equivalent value.

Example: Two capacitors of 10 µF and 20 µF in series give 6.67 µF.

Checking voltage ratings in series

Series connections increase voltage handling. Use the calculator to find the equivalent capacitance, then verify that each capacitor's voltage rating is sufficient for your circuit.

Frequently Asked Questions

How do I calculate equivalent capacitance for capacitors in series?: For two capacitors in series, use the formula 1/C_total = 1/C1 + 1/C2. For three, add 1/C3. The calculator does this automatically when you enter the capacitance values in farads.
Why is the equivalent capacitance less than the smallest capacitor?: In series, the total capacitance is always less than the smallest individual capacitor because the effective plate separation increases, reducing overall capacitance. This is a key property of series connections.
Can I use this calculator for capacitors with different units like microfarads?: The calculator expects values in farads (F). If your capacitors are in microfarads (µF), convert to farads by dividing by 1,000,000 before entering, or use a unit converter first.

Tips & Common Mistakes

Tips

Ensure all capacitance values are in farads (F) before entering. Convert from µF or nF if needed.
For two capacitors, the equivalent capacitance is (C1*C2)/(C1+C2). You can verify the calculator's result with this formula.
If you have more than three capacitors, calculate the equivalent of the first two, then use that result with the next capacitor, and so on.
Remember that in series, the total capacitance is always less than the smallest individual capacitance.

Common Mistakes to Avoid

Forgetting to convert units to farads. Entering microfarads directly will give a wrong result.
Using the formula for parallel capacitors (which is C1 + C2) instead of the series formula.
Assuming the equivalent capacitance is the average of the individual capacitances; it is actually less than the smallest.

Last updated: August 13, 2026