Published on 10/13/2026
A datasheet lists return loss of 14 dB. The amplifier manual asks for VSWR below 1.5:1. A quick check on a calculator, then a second check to be sure. Conversions between VSWR, return loss and reflection coefficient come up in every RF review, and the formulas are short but easy to get wrong.
Short answer: VSWR 1.5:1 equals a reflection coefficient of 0.200, a return loss of 14.0 dB, and 4 percent of the power reflected. VSWR 2:1 is 9.5 dB return loss and 11 percent reflected power.
Use the tables below for a quick lookup in either direction, and the formulas for any value in between.
On This Page
| VSWR | Reflection coefficient | Return loss | Mismatch loss | Power reflected | Power delivered |
|---|---|---|---|---|---|
| 1.05:1 | 0.024 | 32.3 dB | 0.003 dB | 0.1 % | 99.9 % |
| 1.10:1 | 0.048 | 26.4 dB | 0.010 dB | 0.2 % | 99.8 % |
| 1.15:1 | 0.070 | 23.1 dB | 0.021 dB | 0.5 % | 99.5 % |
| 1.20:1 | 0.091 | 20.8 dB | 0.036 dB | 0.8 % | 99.2 % |
| 1.25:1 | 0.111 | 19.1 dB | 0.054 dB | 1.2 % | 98.8 % |
| 1.30:1 | 0.130 | 17.7 dB | 0.075 dB | 1.7 % | 98.3 % |
| 1.40:1 | 0.167 | 15.6 dB | 0.122 dB | 2.8 % | 97.2 % |
| 1.50:1 | 0.200 | 14.0 dB | 0.177 dB | 4.0 % | 96.0 % |
| 1.75:1 | 0.273 | 11.3 dB | 0.336 dB | 7.4 % | 92.6 % |
| 2.00:1 | 0.333 | 9.5 dB | 0.512 dB | 11.1 % | 88.9 % |
| 2.50:1 | 0.429 | 7.4 dB | 0.881 dB | 18.4 % | 81.6 % |
| 3.00:1 | 0.500 | 6.0 dB | 1.249 dB | 25.0 % | 75.0 % |
| 4.00:1 | 0.600 | 4.4 dB | 1.938 dB | 36.0 % | 64.0 % |
| 5.00:1 | 0.667 | 3.5 dB | 2.553 dB | 44.4 % | 55.6 % |
| 10.00:1 | 0.818 | 1.7 dB | 4.807 dB | 66.9 % | 33.1 % |
| Return loss | Reflection coefficient | VSWR | Power reflected |
|---|---|---|---|
| 6 dB | 0.501 | 3.01:1 | 25.12 % |
| 8 dB | 0.398 | 2.32:1 | 15.85 % |
| 10 dB | 0.316 | 1.92:1 | 10.00 % |
| 12 dB | 0.251 | 1.67:1 | 6.31 % |
| 14 dB | 0.200 | 1.50:1 | 3.98 % |
| 15 dB | 0.178 | 1.43:1 | 3.16 % |
| 16 dB | 0.158 | 1.38:1 | 2.51 % |
| 18 dB | 0.126 | 1.29:1 | 1.58 % |
| 20 dB | 0.100 | 1.22:1 | 1.00 % |
| 25 dB | 0.056 | 1.12:1 | 0.32 % |
| 30 dB | 0.032 | 1.07:1 | 0.10 % |
| 40 dB | 0.010 | 1.02:1 | 0.01 % |
Key idea: Higher return loss means a better match. 20 dB return loss is a VSWR of 1.22:1. 30 dB is 1.07:1.
We measure it on every assembly
Every SigmaRF assembly is VNA-swept for VSWR and insertion loss before shipment. Tell us the limit you need.
Talk to an Engineer| VSWR | Quality | Typical use |
|---|---|---|
| Below 1.2:1 | Excellent | Precision, test, calibration |
| 1.2 to 1.5:1 | Good | Most cable assemblies, antennas |
| 1.5 to 2:1 | Acceptable | Basic antenna match, many radios |
| 2 to 3:1 | Poor | Radios may fold back power |
| Above 3:1 | Bad | Fix before use |
In a cable assembly, the measured VSWR includes both connectors and the cable. A long lossy cable looks better than it is because return signal is attenuated twice. For the relationship with insertion loss, see the insertion loss, return loss and VSWR guide on this blog.
Avoid
What is the return loss of 1.5:1 VSWR?
About 14 dB.
What VSWR is 20 dB return loss?
About 1.22:1.
What VSWR is 10 dB return loss?
About 1.92:1.
What is the formula for VSWR from return loss?
VSWR = (1 + 10^(-RL/20)) / (1 - 10^(-RL/20)).
How much power is reflected at 2:1 VSWR?
About 11 percent.
Is 1.5:1 VSWR good?
Yes for most RF assemblies and antennas. For precision work aim for 1.2:1 or better.
Use the tables to move between VSWR, return loss and reflection coefficient. For quick checks remember three points: 1.5:1 is 14 dB, 2:1 is 9.5 dB and 1.2:1 is 20.8 dB.
SigmaRF measures VSWR on every assembly in India (Vadodara) and the USA (Cleveland area), with sweep data across the band and lead times as short as 2 days.
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