Standing wave ratio to return loss
Type a value in SWR to get it in dB instantly.
13.98dB
That's about the same as a good match. About 4% of the power is reflected back.
Convert the other way: dB to SWR
What it means
How good is that match?
SWR is measured at the meter, not at the antenna. Feeder loss flatters the reading: a long lossy cable can make a bad antenna look well matched.
The math
How to convert SWR to dB
Everything comes from the reflection coefficient: Γ = (SWR − 1) ÷ (SWR + 1). Return loss is −20 × log₁₀(Γ) and the reflected power is Γ² × 100 percent.
Example: 1.5 SWR = 13.9794 dB.
Every unit
Your match in every unit
Tables
SWR to dB conversion table
| SWR | dB |
|---|---|
| 1.01 SWR | 46.0639 dB |
| 1.1 SWR | 26.4444 dB |
| 1.2 SWR | 20.8279 dB |
| 1.5 SWR | 13.9794 dB |
| 1.75 SWR | 11.2854 dB |
| 2 SWR | 9.54243 dB |
| 2.5 SWR | 7.35954 dB |
| 3 SWR | 6.0206 dB |
| 4 SWR | 4.43697 dB |
| 5 SWR | 3.52183 dB |
| 10 SWR | 1.743 dB |
dB to SWR conversion table
| dB | SWR |
|---|---|
| 1.01 dB | 17.2192 SWR |
| 1.1 dB | 15.8136 SWR |
| 1.2 dB | 14.4995 SWR |
| 1.5 dB | 11.61 SWR |
| 1.75 dB | 9.96029 SWR |
| 2 dB | 8.72423 SWR |
| 2.5 dB | 6.99662 SWR |
| 3 dB | 5.84804 SWR |
| 4 dB | 4.41943 SWR |
| 5 dB | 3.56977 SWR |
| 10 dB | 1.92495 SWR |
Quick answers
Quick answers
- How many dB is 10 SWR?
- 10 SWR is 1.743 dB.
- How many dB is 1.5 SWR?
- 1.5 SWR is 13.9794 dB.
The units
About these units
Standing wave ratio (SWR)
The ratio of voltages along the feeder. 1:1 is perfect.
Return loss (dB)
How many decibels down the reflected signal is. Higher is better.
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