Add resistor branches
Create as many parallel branches as your circuit requires.
Circuit analysis workspace
Parallel Resistor Calculator
Build a parallel resistor network, mix Ω, kΩ, and MΩ units, and instantly calculate equivalent resistance. Add source voltage to reveal total current, circuit power, and individual branch current.
Resistance Workbench
Add branches and enter each resistor value.
Parallel resistor branches
Minimum 2 · Maximum 20
How it works
Analyze a parallel network in four steps
The calculator converts every resistor to ohms, sums reciprocal resistance, and then calculates optional electrical values from the source voltage.
Enter resistance values
Use ohms, kilo-ohms, or mega-ohms for each branch.
Add source voltage
Voltage reveals total current, branch current, and power.
Review circuit output
See equivalent resistance, conductance, currents, and power.
Understanding resistors in parallel
Resistors are connected in parallel when both terminals of every resistor connect to the same two circuit nodes. Each branch therefore has the same voltage, while current divides between branches according to resistance.
Because every new branch provides another path for current, total conductance increases and equivalent resistance decreases. This is why parallel resistance is always lower than the smallest positive branch resistance.
Parallel resistor formulas
General parallel formula
1 / Rₜ = 1 / R₁ + 1 / R₂ +
... + 1 / Rₙ
Two-resistor shortcut
Rₜ = (R₁ × R₂) / (R₁ + R₂)
Total current
Iₜ = V / Rₜ
Total power
Pₜ = V² / Rₜ
Why branch currents are different
Every branch receives the same voltage, but lower resistance allows more current to flow. The sum of all branch currents equals the total current supplied by the source.
Practical uses
Where parallel resistor calculations are useful
Parallel networks appear in electronics, sensor circuits, load testing, power distribution, and component selection.
Electronic design
Combine standard resistor values to create a required effective resistance.
Sensor networks
Analyze parallel bias, pull-up, pull-down, and sensing resistances.
Load testing
Create lower-resistance test loads using multiple power resistors.
Repair work
Estimate replacement networks when an exact resistor is unavailable.
Electrical learning
Understand conductance, current division, and Ohm’s law.
Power calculations
Estimate branch current and resistor power dissipation before assembly.
Frequently asked questions
Parallel Resistor Calculator FAQs
Common questions about equivalent resistance, units, current, power, and resistor tolerance.
How do I calculate resistors connected in parallel?
Add the reciprocal of every resistance and then take the reciprocal of that total. The formula is 1 divided by R total equals 1 divided by R1 plus 1 divided by R2 and so on.
Is total parallel resistance lower than every branch resistor?
Yes. For positive resistance values, the equivalent resistance of a parallel network is always lower than the smallest individual branch resistance.
What is the shortcut formula for two parallel resistors?
For two resistors, multiply R1 by R2 and divide the result by R1 plus R2.
What happens with equal resistors in parallel?
Divide the resistance of one resistor by the number of identical resistors. For example, four 100-ohm resistors in parallel equal 25 ohms.
Can I mix ohms, kilo-ohms, and mega-ohms?
Yes. Choose the correct unit for each resistor. The calculator converts every branch to ohms before calculating the equivalent value.
How is branch current calculated?
Every parallel branch has the same voltage. Branch current is calculated using Ohm’s law by dividing source voltage by branch resistance.
How is total circuit power calculated?
Total power is voltage squared divided by equivalent resistance. It is also equal to the sum of the power dissipated by all resistor branches.
Does resistor tolerance affect the answer?
Yes. The result uses nominal resistance values. Actual resistance can differ because of tolerance, temperature, heating, measurement error, and connection resistance.
Electrical design reminder
This calculator uses ideal resistance values.
Real circuits can be affected by resistor
tolerance, temperature, wiring resistance,
source limits, and component power ratings.