Current Divider Calculator - Parallel Resistor Current

Agarapu Ramesh — Editor and content reviewer
Editorially reviewed Reviewed by Agarapu Ramesh, science educator (chemistry). LinkedIn
Last reviewed: May 2026 | Ohm's law and standard electrical engineering formulas

Current splits through parallel paths. The lower resistance path takes more current. For two resistors, current through R1 equals total current x R2 / (R1 + R2). It feels backwards the first time, but it works because the other resistor sets the share.

Formula at a glance

  • two branches: I1 = Itotal x R2 / (R1 + R2)
  • two branches: I2 = Itotal x R1 / (R1 + R2)
  • many branches: branch current = total current x conductance branch / conductance total

Field note: Do not use the divider rule on active circuits with supplies, diodes or regulators in the branches. That is no longer a plain resistor divider.

🔀

Current Divider Calculator

Calculate branch currents in parallel circuits

A

Enter values in Ω, separated by commas

Result
—

Formula

2 ResistorsI₁ = I × R₂/(R₁+R₂)
GeneralI_n = I × (R_eq/R_n)

Key Concept

In parallel circuits:
• Same voltage across all branches
• Current divides inversely to resistance
• Lower R = Higher I

Related

Voltage DividerResistor NetworkOhm's Law

How to use the Current Divider Calculator

Use this as a bench check, then compare it with the part marking, tolerance and a meter reading when the circuit matters. Small components are cheap. Bad assumptions are not.

Worked example

Example: 3 A feeding 4 ohms and 8 ohms in parallel gives I through 4 ohms = 3 x 8 / 12 = 2 A. The 8 ohm branch gets 1 A.

Practical checks before you trust the number

  • Parallel branch voltage is the same across every branch.
  • Low-value resistors need power rating checks.
  • Tolerance can shift branch current, especially when resistor values are close.

Common mistake

Do not use the divider rule on active circuits with supplies, diodes or regulators in the branches. That is no longer a plain resistor divider.

Sources and references

Related calculators

Frequently Asked Questions

I_branch = I_total × (R_other ÷ (R_branch + R_other)) for two-branch dividers. Or I_branch = I_total × (G_branch ÷ G_total) for any number of branches, where G = 1/R is conductance. The smaller resistance carries proportionally more current.

For two parallel resistors: II = I_total × RI ÷ (RI + RI); II = I_total × RI ÷ (RI + RI). Note the cross-multiplication — the current through RI depends on RI. This is the dual of the voltage divider formula.

Inversely. Lower-resistance branches carry more current; higher-resistance branches carry less. The ratio is exactly opposite to the resistance ratio. Two equal resistors split current 50/50; a 10 Ω and 30 Ω split 75/25.

II = I_total × RI ÷ (RI + RI). Example: I_total = 6 A, RI = 10 Ω, RI = 20 Ω → II = 6 × 20 ÷ 30 = 4 A; II = 6 × 10 ÷ 30 = 2 A. The lower RI carries more current.

Because current follows the path of least opposition. Lower resistance = lower opposition = higher current share. Ohm's law: I = V ÷ R, same V across parallel branches, so smaller R gives larger I. This is the foundation of current dividing.

Yes. For n branches: I_k = I_total × (G_k ÷ Σ G_i), where G = 1/R. Convert each branch resistance to conductance, sum, divide. Example: three branches at 10 Ω each → each carries one-third of total current, since they're identical.

Yes. Enter total current and branch resistances; the calculator returns each branch current. Useful for verifying parallel-load designs, current sensing networks, and current sharing in parallel power supplies. Always confirm against Ohm's law applied to each branch.