ERP / EIRP Calculator

Calculate effective radiated power from transmitter output, feedline loss, and antenna gain.

Calculate effective radiated power

Enter your transmitter output, system loss, and antenna gain to estimate ERP and EIRP for an amateur radio station.

Use watts for transmitter-output entry, or switch to dBm / dBW if that matches how your radio, amplifier, or regulatory limit is specified.

Common setup examples

Load a realistic station profile to test the calculator quickly.

ERP / EIRP results

100 W input
EIRP
N/A
N/A
ERP
N/A
N/A
Power at antenna input
N/A
N/A
Net system change
N/A
Losses plus gain reference

Intermediate values

StageWattsdBW

Operator notes

    Check feedline loss

    What are ERP and EIRP?

    EIRP is referenced to an isotropic radiator, while ERP is referenced to a half-wave dipole. That means EIRP reads 2.15 dB higher than ERP for the same actual station setup. This tool keeps both values together so you can match whichever standard a regulation, contest rule, or coordination document uses. If you still need to estimate station loss before getting here, start with the Coax Loss Calculator and compare the result against your antenna design.

    Station limits and legal requirements vary by band, service, mode, and jurisdiction. Use these results as a quick planning check, then confirm the actual rule set that applies before transmitting on the relevant band plan.