Standing wave ratio to mismatch loss
Type a value in SWR to get it in dB instantly.
0.1773dB
That's about the same as a good match. About 4% of the power is reflected back.
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 = 0.177288 dB.
Every unit
Your match in every unit
Tables
SWR to dB conversion table
| SWR | dB |
|---|---|
| 1.01 SWR | 0.000107497 dB |
| 1.1 SWR | 0.00985913 dB |
| 1.2 SWR | 0.0360412 dB |
| 1.5 SWR | 0.177288 dB |
| 1.75 SWR | 0.335673 dB |
| 2 SWR | 0.511525 dB |
| 2.5 SWR | 0.881361 dB |
| 3 SWR | 1.24939 dB |
| 4 SWR | 1.9382 dB |
| 5 SWR | 2.55273 dB |
| 10 SWR | 4.80725 dB |
dB to SWR conversion table
| dB | SWR |
|---|---|
| 1.01 dB | 2.67323 SWR |
| 1.1 dB | 2.79525 SWR |
| 1.2 dB | 2.93196 SWR |
| 1.5 dB | 3.3518 SWR |
| 1.75 dB | 3.71582 SWR |
| 2 dB | 4.0954 SWR |
| 2.5 dB | 4.90943 SWR |
| 3 dB | 5.8089 SWR |
| 4 dB | 7.9213 SWR |
| 5 dB | 10.5544 SWR |
| 10 dB | 37.9737 SWR |
Quick answers
Quick answers
- How many dB is 1 SWR?
- 1 SWR is 0 dB.
- How many dB is 10 SWR?
- 10 SWR is 4.80725 dB.
- How many dB is 1.5 SWR?
- 1.5 SWR is 0.177288 dB.
The units
About these units
Standing wave ratio (SWR)
The ratio of voltages along the feeder. 1:1 is perfect.
Mismatch loss (dB)
The power actually lost to the mismatch, in decibels.
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