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RF Exposure Calculator

The FCC has changed its RF-exposure rules, eliminating service-specific exemptions from the need to do a routine RF-safety evalaluation and replacing those exemptions with a formula that applies to all radio services. See the FAQ on the ARRL RF-Exposure page for more information. The rules did not change the exposure limits nor the two-tiered exposure environments for controlled and uncontrolled exposure. The controlled limits generally apply to amateurs and members of their household if those people have been given instructions by the amateur about RF safety. The uncontrolled limits apply in all other circumstances, such as exposure to the general public.

To use the RF Exposure Calculator, fill-in the form below with your operating power, antenna gain, and the operating frequency. Depending on how far above ground the RF source is located, you might want to consider ground reflections — and then click "Calculate".

You may need to run the calculator multiple times to get a complete picture of your situation, i.e. take into account the antenna's lobes and directionality.

View detailed instuctions for each parameter. (opens in new tab/window)


  • Power at Antenna: (Need help with this?) (watts)
  • Mode duty cycle:
  • Transmit duty cycle: (time transmitting)
    You transmit for minutes then receive for minutes (and repeat).
  • Antenna Gain (dBi): (Need help with this?)
  • Operating Frequency (MHz):

Include Effects of Ground Reflections

If you would like to receive future announcements of any FCC news related to RF-exposure or the requirements for amateurs to evaluate their stations, you may optionally provide an email address.

Email Address: (optional)
Comments: (optional)

Results for a controlled environment:

Maximum Allowed Power Density (mw/cm2):
Minimum Safe Distance (feet):
Minimum Safe Distance (meters):

For an uncontrolled environment:

Maximum Allowed Power Density (mw/cm2):
Minimum Safe Distance (feet):
Minimum Safe Distance (meters):

Calculation Sources:
FCC's OST Bulletin 65, originally issued in 1985 and revised in 1997, provides additional guidance for evaluating compliance with the latest FCC policies and guidelines and is available here. A supplement for the Amateur Radio Service (Supplement B) is available here. Likewise a supplement for Mobile and Portable equipment (Supplement C) is available here.

The Javascript contained on this page was derived from a public domain BASIC program written by Wayne Overbeck N6NB and published in the January, 1997 issue of CQ VHF, p. 33. Terms: GNU Licence. This version of the calculator is an iteration of what was generously provided by the Lake Washington Ham Club, Kirkland WA