Calculators
Current Divider Calculator
Split total current across parallel resistors and calculate branch currents, voltage, resistance, and power.
Split a known total current across two to six ideal parallel resistive branches. The calculator also finds equivalent resistance, common branch voltage, and power.
Equivalent resistance571.42857 Ω
Common voltage57.142857 V
Total power5.7142857 W
Branch 1: 57.142857 mA(3.2653061 W)
Branch 2: 28.571429 mA(1.6326531 W)
Branch 3: 14.285714 mA(0.81632653 W)
KCL check: branch currents sum to 100 mA.
This models ideal positive resistances sharing the same two nodes with a known total current. It does not model nonlinear devices, active current-sharing circuits, component tolerances, temperature effects, or AC complex impedance.
About This Tool
A current divider describes how a known current splits when it reaches parallel resistive paths. Because every branch has the same voltage, lower-resistance branches carry more current and higher-resistance branches carry less. This calculator handles two to six ideal resistor branches, calculates the equivalent parallel resistance, derives the shared voltage, reports every branch current and branch power, and checks that the branch currents add back to the entered total. It is useful for circuit-analysis exercises, shunt networks, bias calculations, and quick checks of passive parallel paths.
How To Use It
- Enter the total current arriving at the parallel network and choose A, mA, or µA.
- Enter at least two positive branch resistances and select Ω, kΩ, or MΩ.
- Add or remove branches as needed; the calculator supports up to six resistive branches.
- Read each branch current together with equivalent resistance, common network voltage, branch power, and the Kirchhoff current-law sum check.
Examples
1 A through 100 Ω and 200 Ω
The equivalent resistance is about 66.67 Ω. The 100 Ω branch carries about 0.667 A and the 200 Ω branch about 0.333 A. Their sum is 1 A.
100 mA through 1 kΩ, 2 kΩ, and 4 kΩ
The conductances are in a 4:2:1 ratio, so the branch currents are approximately 57.14 mA, 28.57 mA, and 14.29 mA.
Equal parallel resistors
If three branches all have the same resistance and 30 mA enters the network, symmetry gives 10 mA in each branch.
Useful Notes
General current-divider formula
For parallel resistors, first find Req = 1 / (1/R1 + 1/R2 + ... + 1/Rn). The current in branch n is In = Itotal × Req / Rn. This is equivalent to dividing current in proportion to each branch's conductance 1/R.
Why lower resistance gets more current
All ideal parallel branches share the same voltage. Ohm's law gives I = V/R, so at the same voltage a smaller resistance produces a larger branch current. Current therefore divides inversely with resistance, not directly with resistance.
Two-resistor shortcut
For two branches, I1 = Itotal × R2/(R1 + R2) and I2 = Itotal × R1/(R1 + R2). The other branch's resistance appears in the numerator, a common source of mistakes when using the shortcut.
Kirchhoff current-law check
Kirchhoff's current law says the total current entering a node equals the total current leaving it. For this network, I1 + I2 + ... + In should equal Itotal apart from tiny floating-point rounding differences.
Voltage and power
Once Req is known, the common branch voltage is V = Itotal × Req. Branch power can then be calculated as Pn = In²Rn. These ideal values are useful for analysis, but real component ratings and tolerances still need to be checked separately.
Model limitations
This calculator assumes positive, linear resistances connected across the same two nodes and a known total current. Diodes, transistors, active current-sharing circuits, nonlinear loads, AC phase-dependent impedances, wiring resistance, temperature changes, and component tolerances require a more complete circuit model.
FAQ
Does current divide equally in parallel?
Only when the branch resistances are equal. Otherwise current divides in inverse proportion to resistance, so the lower-resistance branch carries more current.
What is the difference between a voltage divider and a current divider?
A voltage divider normally uses series resistors, where the same current flows and voltage divides. A current divider uses parallel branches, where the same voltage appears across each branch and current divides.
Can I use more than two resistors?
Yes. The general conductance-based formula works for any number of ideal parallel resistors. This interface supports two through six branches.
Can I enter zero-ohm branches?
No. An ideal zero-ohm branch is a short circuit and makes the simple finite-resistance divider model singular. Real short paths also involve source and wiring resistance, so they require a different model.
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