Free tool
SWR & Power Calculator
Convert between forward power, reflected power, SWR, reflection coefficient and mismatch loss.
SWR, reflected power, reflection coefficient and mismatch loss are four ways of describing the same mismatch. This calculator converts between all of them, so you can start from whichever figure your meter actually gives you and see what it means for the power reaching the antenna.
Inputs
Result
Standing wave ratio--:1
Enter values to calculate.
Reflected power-- W
Reflection coefficient--
Mismatch loss-- dB
Radiated power-- W
Mismatch severity--
Gamma = sqrt(Pref / Pfwd) SWR = (1 + gamma) / (1 - gamma)
Mismatch loss = -10 log10(1 - gamma squared) dB
A 2:1 match loses about 0.5 dB. That is a sixth of an S-unit — worth fixing, but not an emergency.
Mismatch loss = -10 log10(1 - gamma squared) dB
A 2:1 match loses about 0.5 dB. That is a sixth of an S-unit — worth fixing, but not an emergency.
What this calculator returns
SWRReflected powerReflection coefficientMismatch lossRadiated power
These figures are calculated from standard formulae and typical published component data. They describe an ideal installation, not yours. Measure your own antenna before cutting wire, and confirm any figure against your equipment and local regulations before relying on it.
SWR reference
| SWR | Reflected power | Reflection coefficient | Mismatch loss |
|---|---|---|---|
| 1.0:1 | 0% | 0.000 | 0.00 dB |
| 1.2:1 | 1% | 0.091 | 0.04 dB |
| 1.5:1 | 4% | 0.200 | 0.18 dB |
| 2.0:1 | 11% | 0.333 | 0.51 dB |
| 3.0:1 | 25% | 0.500 | 1.25 dB |
| 5.0:1 | 44% | 0.667 | 2.55 dB |
| 10:1 | 67% | 0.818 | 4.81 dB |