Velorsen
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Current Divider Calculator

Enter the total current and both resistor values to find the current through R1.

Formula

  • I1 = Itotal × R2/(R1+R2)

Itotal is the current entering the parallel pair, R1 and R2 are the two resistors, and I1 is the current through R1.

About this calculation

Two resistors in parallel split a current in the inverse ratio of their resistances: the smaller resistance carries the larger share. Enter the total current and both resistor values to find the current in one branch, which is the standard way to work out what a shunt or a branch of a parallel network carries.

Assumptions and limits

  • It models exactly two parallel branches. A third path changes both the total resistance and the split.
  • The total current is taken as given, as if it were fixed by the rest of the circuit or set by a current source.
  • The resistors are ideal, so their tolerance and any temperature drift are not included.

A worked example

5 A fed into a parallel pair of 1 Ω and 4 Ω divides as I(1 Ω) = 5 × 4 / (1 + 4) = 4 A, leaving 1 A in the 4 Ω branch — four times the current in the branch with a quarter of the resistance.

See also Voltage Divider and Ohm's Law.