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Science & Engineering

Parallel Resistance Calculator

Calculate the equivalent resistance of resistors in parallel, total conductance and current for a given voltage.

Your inputs

Results

Equivalent resistance

56.896552 Ω

Total conductance
0.01757576 S
Total current
0.210909 A

✓Exact calculation — rounded only for display

What this calculator does

In parallel, each resistor sees the same voltage and their conductances add, so the total is lower than the smallest resistor.

Formula and method

1 ÷ R_eq = 1 ÷ R₁ + 1 ÷ R₂ + …; two resistors: R₁R₂ ÷ (R₁ + R₂)

Worked example

Calculated by this tool with its default inputs:

Inputs

  • Resistances (Ω): 100, 220, 330
  • Voltage across them (optional): 12

Results

  • Equivalent resistance: 56.896552 Ω
  • Total conductance: 0.01757576 S
  • Total current: 0.210909 A

How to read the results

Adding a parallel branch always lowers the equivalent resistance.

Assumptions and limitations

  • A 0 Ω branch would short the circuit and is rejected.

These are educational estimates. Electrical, structural and other safety-critical work must comply with local codes and be designed or checked by a qualified professional.

Questions

What are two equal resistors in parallel?

Half the value of one.

Methodology and verification

Result type
Exact mathematical calculation (rounded only for display)
Formula version
1.0
Automated verification
3 reference and validation test cases, checked against independently computed values. The site cannot be built if any of them fail.
Editorial review
Awaiting human editorial review. The explanation was drafted with AI assistance; the formula and examples are verified by the automated tests above.

Privacy

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