Calculator · Safety

RF Exposure Distance Estimator

Estimate the minimum safe distance from your transmitting antenna based on power output, frequency, antenna gain, and duty cycle. Based on FCC OET Bulletin 65 simplified method.

This tool is an estimate only — for general guidance and exam study. For a formal FCC RF exposure evaluation, use the ARRL's calculator at arrl.org or the FCC's OET Bulletin 65 methodology. Not a substitute for professional evaluation.

Estimate Safe Distance

Transmit Power (Watts)

Frequency (MHz)

Antenna Gain (dBi)

Duty Cycle (%)

FCC RF Exposure Limits — General Population

Frequency Range	MPE Limit (mW/cm²)	Notes
30–300 MHz	0.2 mW/cm²	Most restrictive range — includes 6m, 2m, 1.25m
300–1500 MHz	f/1500 mW/cm²	70cm falls here (~0.29 mW/cm² at 440 MHz)
1500–100,000 MHz	1.0 mW/cm²	23cm and above

Does my HT require an RF exposure evaluation?

No. Handheld transceivers operating at 5 watts or less are categorically excluded from the formal RF exposure evaluation requirement under FCC Part 97.13(c)(1). However, you should still follow basic common sense: keep the antenna away from your head while transmitting, and limit transmission duration during extended operating sessions.
What is duty cycle and why does it matter?

Duty cycle is the fraction of time your transmitter is actually transmitting during an operating session. FM voice conversation is roughly 50% (half transmitting, half listening). An APRS beacon transmitting every 30 seconds for 1-second bursts is about 3%. A sustained carrier test is 100%. Lower duty cycle reduces average RF exposure proportionally — a 100W station with 20% duty cycle has the same average exposure as a 20W station at 100% duty cycle.