Parallel Resistor Calculator

What Is Parallel Resistance?

When resistors share the same two nodes, they are in parallel. Each branch sees the same voltage, and current splits among them. The equivalent resistance is always less than the smallest individual resistor because more paths carry current.

Parallel Resistor Formula

For n resistors in parallel:

$$\frac{1}{R_{eq}} = \frac{1}{R_1} + \frac{1}{R_2} + \cdots + \frac{1}{R_n}$$

Conductance adds directly: $G_{eq} = G_1 + G_2 + \cdots + G_n$ where $G = 1/R$. For two resistors, a shortcut is $R_{eq} = (R_1 R_2) / (R_1 + R_2)$.

Practical Uses

Parallel combinations appear in current dividers, LED ballast networks, and precision trimming. Adding a resistor in parallel lowers total resistance. Removing one branch raises it.

Frequently Asked Questions

Why is parallel resistance smaller than any single resistor?

Parallel branches offer more paths for current. More conductance means lower equivalent resistance.

Is voltage the same across parallel resistors?

Yes. All parallel components share the same potential difference between their common nodes.

What happens if one resistor value is zero?

A zero-ohm branch shorts the network. Equivalent resistance becomes zero and current is limited only by the source.

Can I mix resistor values in any unit?

Enter all values in ohms. Convert kilohms or megohms to ohms first (1 kΩ = 1000 Ω).

How many resistors can I combine?

This tool supports up to six parallel resistors. The same reciprocal-sum formula applies regardless of count.

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What Is Parallel Resistance?

Parallel Resistor Formula

Practical Uses

Frequently Asked Questions

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