Current Divider Calculator
Calculate current through parallel resistors using the current divider rule
Amperes (A)
Ohms (Ω)
Ohms (Ω)
How to Use This Calculator
Enter Total Current
Enter the total current flowing into the parallel resistor network in amperes (A). This is the current from the source.
Enter Resistor Values
Enter the resistance values of both parallel resistors in ohms (Ω). These are the two resistors in parallel.
Calculate Currents
Click calculate to see how the current divides between the two parallel resistors. The calculator shows current through each resistor.
Formula
I1 = Itotal × R2 / (R1 + R2)
I2 = Itotal × R1 / (R1 + R2)
Where:
- I1 = Current through resistor R1 (A)
- I2 = Current through resistor R2 (A)
- Itotal = Total current (A)
- R1, R2 = Resistor values (Ω)
Key Points:
- Current divides inversely with resistance - smaller resistor gets more current
- For equal resistors, current divides equally (50% each)
- Sum of branch currents equals total current (I1 + I2 = Itotal)
- Opposite of voltage divider - current divider uses parallel resistors
Example 1:
Total Current = 10 A, R1 = 1000 Ω, R2 = 2000 Ω
I1 = 10 × 2000 / (1000 + 2000) = 20,000 / 3000 = 6.67 A
I2 = 10 × 1000 / (1000 + 2000) = 10,000 / 3000 = 3.33 A
Example 2:
Total Current = 5 A, R1 = 100 Ω, R2 = 100 Ω (equal resistors)
I1 = 5 × 100 / (100 + 100) = 500 / 200 = 2.5 A
I2 = 5 × 100 / (100 + 100) = 2.5 A (equal current)
About Current Divider Calculator
The Current Divider Calculator is a free online tool that helps you calculate how current divides between parallel resistors. The current divider rule is the dual of the voltage divider rule and is essential for analyzing parallel circuits. When current flows through parallel resistors, it divides inversely proportional to resistance - the smaller resistor receives more current.
When to Use This Calculator
- Circuit Analysis: Analyze parallel resistor networks and current distribution
- Power Supply Design: Calculate current through parallel loads
- Current Limiting: Design current-limiting circuits with parallel branches
- Educational Purposes: Learn about current division and parallel circuits
- Circuit Troubleshooting: Verify current distribution in existing circuits
Why Use Our Calculator?
- ✅ Accurate Calculations: Uses the correct current divider formula
- ✅ Easy to Use: Simple interface requiring total current and two resistor values
- ✅ Dual Output: Shows current through both parallel resistors
- ✅ Verification: Displays sum of currents to verify calculations
- ✅ Free Tool: No registration or payment required
- ✅ Educational: Includes formulas and examples for learning
Common Applications
Parallel Load Circuits: When multiple loads are connected in parallel to a power supply, the current divides between them. A 10A source might supply 6A to a 2Ω load and 4A to a 3Ω load, with the smaller resistance getting more current.
Current Shunts: Current measurement shunts use the current divider principle. A small shunt resistor diverts a known fraction of current for measurement, while the rest flows through the main path.
Power Distribution: In power distribution systems, parallel branches receive current proportional to their conductance (inverse of resistance). Lower resistance paths carry more current.
Circuit Protection: Parallel fuse or circuit breaker arrangements use current division to ensure proper protection. Each branch receives current based on its resistance.
Tips for Accurate Results
- Enter all values in base units (amperes for current, ohms for resistance)
- Current divides inversely with resistance - smaller resistor gets more current
- For equal resistors, current divides equally (50% each)
- Sum of branch currents must equal total current
- Consider resistor tolerance - actual current may vary slightly
- This calculator assumes ideal resistors with no parasitic effects
Frequently Asked Questions
What is the current divider rule?
The current divider rule states that current through parallel resistors divides inversely proportional to resistance. The smaller resistor receives more current. Formula: I1 = Itotal × R2 / (R1 + R2).
How is current divider different from voltage divider?
Current divider applies to parallel resistors (current divides), while voltage divider applies to series resistors (voltage divides). Current divides inversely with resistance, while voltage divides directly with resistance.
What happens if the resistors are equal?
If two parallel resistors are equal, current divides equally. Each resistor receives 50% of the total current, regardless of the resistance value.
Can I use this for more than two resistors?
This calculator handles two resistors. For more resistors, use: I1 = Itotal × (Rtotal / R1), where Rtotal is the parallel equivalent resistance. You'll need to calculate Rtotal first using 1/Rtotal = 1/R1 + 1/R2 + 1/R3 + ...
Does this work for AC circuits?
The current divider rule works for AC circuits with resistive loads. For reactive components (inductors, capacitors), you need to use impedance instead of resistance and consider phase relationships.