SWR / Return Loss Calculator

Convert SWR to return loss, reflected power, and mismatch information.

Convert mismatch information

Use SWR or return loss to estimate reflected power, reflection coefficient, and mismatch loss without doing the RF math by hand.

Lower SWR and higher return loss both indicate a better match. Forward power is optional, but it lets the calculator estimate reflected watts directly.

Common examples

Load a typical mismatch case to check the conversion quickly.

SWR / return loss results

SWR mode
Good match
SWR
N/A
Standing wave ratio
Return loss
N/A
Return loss in dB
Reflection coefficient
N/A
Magnitude of Γ
Reflected power
N/A
Percentage of forward power
Reflected power in watts
N/A
Shown when forward power is entered
Mismatch loss
N/A
Additional loss from the mismatch alone

Operator notes

    Check feedline loss →

    About SWR and Return Loss

    Amateur radio operators use SWR and return loss while tuning antennas, checking feedlines, and deciding whether a matching network is doing its job. SWR is the easier number to talk about in the shack, while return loss is a clearer dB-based way to describe how much energy is being sent back toward the radio. Pair this with the Coax Loss Calculator when you want to separate mismatch issues from feedline loss, or compare it against your antenna dimensions after retuning.

    Show formulas

    Reflection coefficient: (SWR - 1) / (SWR + 1)

    Return loss: -20 log10(|Γ|)

    Reflected power %: |Γ|² × 100

    Mismatch loss: -10 log10(1 - |Γ|²)