VSWR Calculator
Calculate VSWR, reflection coefficient and return loss from impedance mismatch for antenna and RF work using this free browser-based calculator.
100% FreeRuns in your browserIntermediate
Enter Values
Minimum 0
Minimum 0
Enter your values and press Calculate to see results.
How to use this calculator
- Enter the forward and reflected power in watts.
- Read VSWR, return loss and reflection coefficient.
How it works
Reflection coefficient Γ = √(reflected ÷ forward); VSWR = (1 + Γ) ÷ (1 − Γ); return loss = −10·log10(reflected ÷ forward).
Worked example
100 W forward, 5 W reflected. VSWR ≈ 1.58:1, return loss ≈ 13 dB.
Common mistakes
- Reflected power can't exceed forward power.
- Confusing a high VSWR (bad match) with high power.
Frequently asked questions
What VSWR is acceptable?
1:1 is perfect; under about 1.5:1 is generally good, and many rigs fold back power above ~2:1 or 3:1.
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Explore more in Telecommunications & Radio.
Cite this tool
Zerdly. (2026). VSWR Calculator. Retrieved from https://www.zerdly.com/tools/vswr-calculator/
Tip: Enter any known values to calculate the remaining results.
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