SWR (Standing Wave Ratio) affects the power output of your radio. The following table shows the effect of SWR for a transmitter with 4 watts of transmitted power.
| SWR READING | % OF LOSS | ERP* | WATTS AVAILABLE |
| 1.0:1 | 0.0% | 100.0% | 4.00 |
| 1.1:1 | 0.2% | 99.8% | 3.99 |
| 1.2:1 | 0.8% | 99.2% | 3.97 |
| 1.3:1 | 1.7% | 98.3% | 3.93 |
| 1.4:1 | 2.8% | 97.2% | 3.89 |
| 1.5:1 | 4.0% | 96.0% | 3.84 |
| 1.6:1 | 5.3% | 94.7% | 3.79 |
| 1.7:1 | 6.7% | 93.3% | 3.73 |
| 1.8:1 | 8.2% | 91.8% | 3.67 |
| 2.0:1 | 11.1% | 88.9% | 3.56 |
| 2.2:1 | 14.1% | 85.9% | 3.44 |
| 2.4:1 | 17.0% | 83.0% | 3.32 |
| 2.6:1 | 19.8% | 80.2% | 3.21 |
| 3.0:1 | 25.0% | 75.0% | 3.00 |
| 4.0:1 | 36.0% | 64.0% | 2.56 |
| 5.0:1 | 44.4% | 55.6% | 2.22 |
| 6.0:1 | 51.0% | 49.0% | 1.96 |
| 7.0:1 | 56.3% | 43.8% | 1.75 |
| 8.0:1 | 60.5% | 39.5% | 1.58 |
| 9.0:1 | 64.0% | 36.0% | 1.44 |
| 10.0:1 | 66.9% | 33.1% | 1.32 |
