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VSWR Calculator.

Calculate voltage standing-wave ratio from reflection-coefficient magnitude.

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VSWR: 1.5

VSWR

0.000000
Return loss: 13.9794 dB

Return loss

0.000000dB

Results update automatically as you type.

Use Cases

Antenna Matching Assessment

Quickly evaluate how well an antenna is matched to its feedline by entering the reflection coefficient magnitude from a network analyzer or datasheet.

Example: If |Γ| = 0.2, VSWR = 1.5, indicating a good match.

RF System Troubleshooting

Use the VSWR value to identify impedance mismatches in RF components like cables, connectors, or filters, helping to diagnose signal reflections.

Example: A VSWR of 3.0 suggests a significant mismatch that may need correction.

Frequently Asked Questions

What is VSWR and why is it important?
VSWR (Voltage Standing Wave Ratio) measures how well a transmission line is matched to its load. It is derived from the reflection coefficient magnitude. A VSWR of 1:1 indicates a perfect match, while higher values indicate more reflected power, which can reduce efficiency and cause signal loss.
How do I use this VSWR calculator?
Simply enter the magnitude of the reflection coefficient (|Γ|) in the provided field. The calculator will compute the VSWR using the formula VSWR = (1 + |Γ|) / (1 - |Γ|). Ensure the value is between 0 and 1.
What is the range of VSWR values?
VSWR ranges from 1 (perfect match, |Γ|=0) to infinity (total reflection, |Γ|=1). In practice, a VSWR below 2 is often acceptable, but lower is better for efficient power transfer.

Tips & Common Mistakes

Tips

  • Ensure the reflection coefficient magnitude is between 0 and 1. Values outside this range are invalid.
  • For a perfect match, |Γ| = 0 gives VSWR = 1. For total reflection, |Γ| = 1 gives infinite VSWR.
  • Use this calculator as a quick reference; for precise measurements, use calibrated equipment.
  • Remember that VSWR is dimensionless, so no units are needed.

Common Mistakes to Avoid

  • Entering a negative value for |Γ|, which is physically impossible.
  • Confusing VSWR with return loss; they are related but different metrics.
  • Assuming a VSWR of 1 is always achievable; in practice, some mismatch is inevitable.

Last updated: August 13, 2026