Parallel resistance calculator

Combine two to four resistors in parallel and explore the equivalent resistance.

Schematic

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Results

Total resistance687.5 Ω2 components in parallel

Network results
Network current	7.27 mA
Applied voltage	5 V
Total power	36.36 mW

Advanced results

Individual resistor results
R1 voltage	5 V
R1 current	5 mA
R1 power	25 mW
R2 voltage	5 V
R2 current	2.27 mA
R2 power	11.36 mW

Ideal resistors. Change the source voltage in Advanced to see current and power.

How parallel resistance works

Parallel resistors share the same voltage. Each branch carries a current equal to that voltage divided by its resistance. Adding branches creates more paths for current, so the equivalent resistance is smaller than the smallest branch resistance.

\frac{1}{R_T} = \frac{1}{R_1} + \frac{1}{R_2} + \cdots + \frac{1}{R_n}

Choose two to four resistors. For two equal resistors, the equivalent resistance is half either value. Change the voltage under Advanced to explore total current, branch currents and resistor power.

Edit the component values on the canvas, or choose Try in CircuitSim to simulate your circuit.

Do the math

Selected input values
R1	1 kΩ
R2	2.2 kΩ
V1	5 V

Equivalent resistance: $\frac{1}{R_T} = \sum_i \frac{1}{R_i}$
Substitute the selected values:
$\left(\frac{1}{1\,\mathrm{k\Omega}} + \frac{1}{2.2\,\mathrm{k\Omega}}\right)^{-1}$
≈ 687.5 Ω
Network current: $I = \frac{V}{R_T}$
$= \frac{5\,\mathrm{V}}{687.5\,\mathrm{\Omega}}$
≈ 7.27 mA
Total power: $P = V I$
$= 5\,\mathrm{V} \times 7.27\,\mathrm{mA}$
≈ 36.36 mW

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Parallel resistance calculator

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How parallel resistance works

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