Calculadora de Resistência em Série e Paralelo
- Created by
- Renato Passos, Eng. de Software
- Reviewed by
- Renato Passos, Eng. de Software
Last updated: Apr 18, 2026
Formula
Rs = R₁+R₂+R₃ | 1/Rp = 1/R₁+1/R₂+1/R₃
About this calculator
This calculator determines the equivalent resistance of up to three resistors connected in series or in parallel. In a series circuit, the total resistance is the direct sum of the individual values: Rs = R1 + R2 + R3. In a parallel circuit, the reciprocal of the total resistance is the sum of the reciprocals: 1/Rp = 1/R1 + 1/R2 + 1/R3. The tool provides both calculations simultaneously, making it easy to compare the two configurations.
How it works: enter the resistor values (in ohms) in the corresponding fields and click 'Calculate'. The calculator processes both formulas and displays the results for series and parallel. It is useful for electricity students, technicians, and hobbyists who need to design or analyze circuits quickly without manual calculations.
Use this calculator in situations such as sizing resistors in electronic circuits, verifying associations in LED lighting projects, or in teaching labs to check experimental results. Remember that series resistance is always greater than the largest individual resistor, while parallel resistance is smaller than the smallest resistor.
Important precautions: ensure all values are in the same unit (ohms, kΩ, MΩ). The calculator accepts decimal numbers but does not automatically convert between units. Also, for more than three resistors, parallel calculations require repeating the process or using extended formulas. Verify that the resistors are actually in series or parallel in the real circuit, as incorrect connections can lead to wrong results.
Frequently asked questions
Can I use values in kΩ or MΩ in the calculator?
Yes, as long as all resistors are in the same unit. The calculator does not auto-convert; mixing ohms and kΩ will give incorrect results.
What if I leave a field blank?
The calculator treats it as zero, which can cause division by zero in parallel calculations. Fill all fields with positive values.
Does it work for more than three resistors?
Not directly. For series, just add more resistors manually. For parallel, you can calculate two at a time or use an extended formula.
What is the difference between series and parallel?
In series, current flows through all resistors sequentially, increasing total resistance. In parallel, current splits, decreasing total resistance.
Can I use this calculator for capacitors?
No, the formulas are different: series capacitors use the parallel resistor formula and vice versa. This calculator is specific to resistors.