Current Divider Calculator
Find how an input current splits between parallel resistor branches.
Input
ℹ Current divides inversely with resistance — the smallest resistor carries the most current.
Results
Parallel Resistance—
Branch Currents—
💡 Usage & Formula
For resistors in parallel, each branch current is: I_k = Iin × (1/R_k) / Σ(1/R_i).
Usage: Enter the total current and two or more branch resistances; the currents always sum back to Iin.
When you need it: Finding how a current splits between parallel branches — sizing a shunt, balancing parallel LED strings, or checking how paralleled resistors share a load.
Worked example: 10 mA into 100 Ω ∥ 300 Ω: the 100 Ω branch takes 10mA × 300/(100+300) = 7.5 mA and the 300 Ω branch takes 2.5 mA — more current flows through the smaller resistor.
Tips & gotchas:
- Current splits inversely to resistance — the opposite of how a voltage divider splits voltage.
- For two branches, one branch gets
Itotal × (Rother / (R1 + R2)); note it's the other resistor on top. - All branches must share the same two nodes for the formula to hold.
- Tolerance mismatch makes parallel devices share unevenly — a real concern for paralleled MOSFETs or diodes.
📖 References:
Current divider (Wikipedia)