What is a good VSWR value?

For most RF systems, VSWR ≤ 2.0 (return loss ≥ 9.5 dB, Γ ≤ 0.33) is acceptable. Antenna systems often target VSWR ≤ 1.5 (≥ 14 dB), and sensitive receiver front-ends may require VSWR ≤ 1.2 (≥ 20.8 dB).

What is the relationship between VSWR and return loss?

Return loss (dB) = −20 × log₁₀((VSWR − 1)/(VSWR + 1)). A higher return loss means less reflected power and a better impedance match. VSWR = 1.0 is a perfect match with infinite return loss.

What is the reflection coefficient?

The reflection coefficient Γ (gamma) is the ratio of the reflected voltage wave to the incident voltage wave. It ranges from 0 (perfect match) to 1 (total reflection). Γ = (VSWR − 1) / (VSWR + 1).

What is mismatch loss?

Mismatch loss is the power lost to reflection expressed in dB: ML = −10 × log₁₀(1 − Γ²). For example, a VSWR of 2.0 causes about 0.51 dB of mismatch loss — roughly 11 % of the transmitted power is lost.

Can I convert return loss back to VSWR?

Yes. Given return loss RL in dB: Γ = 10^(−RL/20), then VSWR = (1 + Γ)/(1 − Γ). The Reverse Converter section on this page does exactly that.

VSWR to Return Loss Converter

Enter a VSWR value and instantly get return loss in dB and the reflection coefficient — core RF metrics for antenna and transmission-line work.

VSWR → Return Loss

Enter a VSWR value (≥ 1.0) to get return loss and reflection coefficient.

VSWR

Return Loss → VSWR

Enter return loss in dB (positive number) to convert back to VSWR and Γ.

Return Loss (dB)

Common VSWR Reference Values

VSWR	Return Loss	Γ	Power Reflected	Typical Use

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Summary

This tool converts Voltage Standing Wave Ratio (VSWR) to return loss in decibels and the corresponding reflection coefficient (Γ). VSWR measures impedance mismatch on a transmission line; return loss and reflection coefficient express the same mismatch in different units used across RF datasheets, VNA readouts, and antenna specifications. All three quantities are mathematically equivalent — the converter lets you move between them without memorizing the formulas.

How it works

Enter a VSWR value (must be ≥ 1.0; a perfect match is VSWR = 1.0).
The reflection coefficient Γ is computed as Γ = (VSWR − 1) / (VSWR + 1).
Return loss is calculated as RL = −20 × log₁₀(Γ) in dB.
Mismatch loss (power lost due to the mismatch) is also shown.
The power reflected and transmitted percentages update in real time.
Use the reverse section to convert return loss back to VSWR.

Use cases

Verify antenna performance against a specified return loss threshold (e.g., ≤ −10 dB).
Translate VNA S11 readings (in dB) into VSWR for datasheets.
Check if a coax connector or cable assembly meets system match requirements.
Compare impedance match quality across different amplifier or filter designs.
Convert manufacturer-specified VSWR to return loss when budgeting a link.
Teach RF transmission-line theory with live numerical examples.

Frequently Asked Questions

Last updated: 2026-06-11 · Reviewed by Nham Vu