Enter two antenna heights to see each radio horizon and the clear-path limit between them. Then pick a station type and channel group to check the FCC power limit. It runs in your browser; nothing is stored.

GMRS range and antenna height estimator

1. Antenna heights

Your antenna height above ground (feet)

About 5–6 ft for a handheld at head height; roof height for a vehicle or base antenna.

Other station’s antenna height (feet)

Another handheld, a vehicle, or a repeater antenna on a tower or hill.

Terrain allowance (% of the clear-path horizon to plan on)

100 = flat, open ground or water. Hills, trees and buildings block UHF; try 50 or lower to plan conservatively.

2. Station and channel (power check)

Station type

Channel group

Your estimate

Your radio horizon (miles)

Other station’s radio horizon (miles)

Clear-path line-of-sight limit (miles)

Planning range after your terrain allowance (miles)

Power limit: mobile, repeater and base stations: up to 50 W transmitter output on the main channels; fixed stations up to 15 W (95.1767(a)).

Power limit: 5 W ERP for mobile, handheld and base stations on the 462 MHz interstitial channels (95.1767(b)). Repeaters and fixed stations may not transmit here (95.1763(b)).

Power limit: handhelds only, 0.5 W ERP, 12.5 kHz bandwidth (95.1763(d), 95.1767(c), 95.1773(b)).

Repeater input: mobile, handheld and control stations transmit here only through a repeater or for brief tests (95.1763(c)). Main-channel power limits apply (95.1767(a)).

Not allowed: only handheld units may transmit on the 467 MHz interstitial channels (95.1763(d)).

Not allowed: repeaters and fixed stations may not transmit on the 462 MHz interstitial channels (95.1763(b)).

Check the rule: repeaters and base stations are not listed for the 467 MHz main channels (95.1763(c)). Repeaters transmit on 462 MHz main channels.

How this is calculated

Radio horizon (miles) ≈ √(2 × antenna height in feet). This is the standard smooth-earth approximation using a 4/3 effective Earth radius to allow for normal atmospheric bending. The two horizons add up to the longest clear path. Real range is usually shorter: GMRS is UHF and depends mainly on line of sight, so terrain, trees, buildings, cable loss and the receiving radio all matter. The FCC says to expect one to twenty-five miles depending on station class, terrain and repeater use.

Sources: FCC rules 47 CFR Part 95 Subpart E (eCFR, checked Oct 12, 2026) and the FCC GMRS page and personal-service fee table. General information, not legal advice.

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How the math works

Radio horizon (miles) ≈ √(2 × antenna height in feet). This is the smooth-earth approximation with a 4/3 effective Earth radius.
Clear-path limit = your horizon + the other station’s horizon.
Planning range = clear-path limit × your terrain allowance ÷ 100.

Heights	Horizons	Clear-path limit
6 ft + 6 ft	3.5 + 3.5 mi	6.9 mi
30 ft + 7 ft	7.7 + 3.7 mi	11.5 mi
200 ft + 6 ft	20.0 + 3.5 mi	23.5 mi

Power limits come from 95.1767 and channel permissions from 95.1763. Terrain usually cuts real range below the clear-path limit; the FCC’s own estimate is one to twenty-five miles. See GMRS range explained and antenna height and gain.