Current Divider Calculator
This current divider calculator finds how a total current splits between two resistors in parallel. Enter the total current and the two resistances, and the current divider calculator returns the current through each branch and the equivalent resistance. It is the parallel-circuit partner of the voltage divider.
Results
The Current Divider Calculator is part of our DC/AC Circuits collection. Browse more dc/ac circuits to size, convert, and check your work alongside this tool.
What the current divider calculator shows
When current reaches two parallel paths, more of it flows through the path with less resistance. The current divider calculator applies the current division rule to give the share in each branch. Use it as a current division calculator for shunts, sensing resistors, and parallel loads.
Current division calculator formula
The current division calculator uses the current divider rule for two branches:
Note that each branch current uses the other branch's resistance on top. The equivalent resistance is R₁R₂ ÷ (R₁ + R₂).
Current divider calculator example
A total of 1 A splits between 100 Ω and 200 Ω. The current divider calculator gives:
The equivalent resistance is 66.7 Ω. The smaller resistor carries twice the current.
How to use the current divider calculator
Enter the total current in amps and the two resistances in ohms. The current divider calculator returns the current through R1, the current through R2, and the equivalent parallel resistance. The two branch currents always add up to the total.
Reading the current divider calculator result
The branch with the lower resistance always takes the larger current, in inverse proportion to the resistances. Both branches see the same voltage, so you can check the result: 0.667 A × 100 Ω = 66.7 V and 0.333 A × 200 Ω = 66.7 V. Multiply each branch current squared by its resistance for the power it dissipates.
When to use the current division calculator
- Designing an ammeter shunt with the current division calculator
- Sharing load current between parallel resistors
- Checking parallel LED or heater branches
- Solving circuit theory problems
Common current divider calculator mistakes
- Using the same branch resistance on top. I1 uses R2, not R1.
- Applying it to series circuits. Series circuits carry one current; use a voltage divider.
- Ignoring power ratings. Check I²R for each resistor.
Tips for accurate results
- Check that the branch currents add to the total.
- Confirm both branches give the same voltage.
- Choose resistor wattage with margin.
Current divider calculator for more branches
With more than two parallel branches, find the equivalent resistance first, then each branch current is I × Req ÷ Rn. The same rule as the two-branch current divider calculator, just generalised. Each branch current can then be checked with the Ohm's law calculator, since every branch shares the same voltage.
Resistor divider current calculator for shunts
An ammeter shunt is a tiny resistor in parallel with a meter, so most of the current bypasses the meter. A resistor divider current calculator shows how small the shunt must be: to pass 99 percent of the current, the shunt must be about one ninety-ninth of the meter resistance.
Resistor divider current calculator reference (1 A total)
| R1 | R2 | I1 | I2 |
|---|---|---|---|
| 100 Ω | 100 Ω | 0.500 A | 0.500 A |
| 100 Ω | 200 Ω | 0.667 A | 0.333 A |
| 100 Ω | 900 Ω | 0.900 A | 0.100 A |
| 1 Ω | 99 Ω | 0.990 A | 0.010 A |
Current Divider Calculator FAQ
What is the current divider rule?
In two parallel branches, I1 = I × R2 / (R1 + R2) and I2 = I × R1 / (R1 + R2).
Which branch gets more current?
The branch with the lower resistance, in inverse proportion to the resistance values.
How is a current divider different from a voltage divider?
A current divider splits current between parallel branches; a voltage divider splits voltage across series resistors.
Can I use it for more than two branches?
For many branches, find each current as I × Req / Rn, where Req is the total parallel resistance.