Current Divider Calculator

What Is a Current Divider?

A current divider splits total current between parallel resistors inversely proportional to their resistance. The smaller resistor carries more current because parallel branches share the same voltage but offer different conductance.

Current Divider Formulas

$$I_1 = I \frac{R_2}{R_1 + R_2}$$ $$I_2 = I \frac{R_1}{R_1 + R_2}$$

$I$ is total current entering the parallel pair, and $I_1$ and $I_2$ are branch currents through $R_1$ and $R_2$. The branch currents always sum to the total: $I_1 + I_2 = I$.

Example: 1 A through 300 Ω and 100 Ω in parallel gives $I_1 = 1 \times 100/400 = 0.25$ A and $I_2 = 0.75$ A.

Applications

Current dividers appear in biasing networks, sensor shunts, parallel LED strings, and power distribution where branch currents must be estimated from known resistances.

Frequently Asked Questions

How is a current divider different from a voltage divider?

A voltage divider splits voltage in series; a current divider splits current in parallel. Voltage dividers use resistances in the same branch; current dividers use resistances across the same nodes.

Why does the smaller resistor get more current?

Parallel branches share the same voltage. By Ohm's law, lower resistance means higher current for the same voltage drop.

Do branch currents always add to the total?

Yes. Kirchhoff's current law requires $I_1 + I_2 = I$ for two parallel branches with no other paths.

Can I use this for more than two resistors?

Yes. For resistor $R_i$ in a parallel group, $I_i = I \times (1/R_i) / \sum (1/R_j)$. This calculator handles the two-resistor case.

What units should I use?

Use amperes for current and ohms for resistance. Mixing units without conversion gives incorrect results.

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What Is a Current Divider?

Current Divider Formulas

Applications

Frequently Asked Questions

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