Walkie-Talkie Range Calculator
How far will your FRS, GMRS or ham radio really reach? Pick the radios, antenna heights, terrain and trees. The estimate comes from a published propagation model, checks the FCC power limits for your channel, and shows its working.
How is the range calculated?
The calculator chains five steps. Each is a published formula or a clearly labeled editorial estimate, and the working table under the result shows the numbers for your inputs.
1. Radio horizon
VHF and UHF signals travel close to line of sight, bent slightly by the atmosphere. With the standard 4/3 effective earth radius, the radio horizon is d (km) = 4.12 x (sqrt(h1) + sqrt(h2)) with heights in meters, or d (mi) = 1.41 x (sqrt(h1) + sqrt(h2)) with heights in feet. Two handhelds at 5 ft have a horizon of about 6.3 miles. No amount of power gets past it, which is why antenna height matters so much.
2. Median path loss (Egli model)
Inside the horizon, the loss comes from the Egli model (J. J. Egli, "Radio Propagation Above 40 MC Over Irregular Terrain", Proceedings of the IRE, October 1957), an empirical fit to measurements from about 40 to 1,000 MHz. Its closed form is P_R = G_T G_R (h_T h_R / d^2)^2 (40 / f)^2 P_T, which in decibels with isotropic antennas, distance in km, heights in m and frequency in MHz is:
L = 120 + 40 log(d) - 20 log(h_T) - 20 log(h_R) + 20 log(f / 40)
The last term is Egli's terrain factor, the extra median loss of irregular terrain over smooth earth: 21.3 dB at 462 MHz and 11.3 dB at 146 MHz. The calculator scales it by terrain class: none of it for flat open ground or water (pure plane-earth loss), half of it for gently rolling ground (an editorial interpolation between the two cases Egli's formula covers), and all of it for hilly terrain. The loss is never allowed below free-space loss, 32.45 + 20 log(f) + 20 log(d), which matters only at short distances or from great heights.
3. Extra losses
| Loss | Value at 462 MHz | Source |
|---|---|---|
| A ridge blocks the path | 20.5 dB on top of rolling ground | ITU-R P.526 single knife-edge approximation, J(v) = 6.9 + 20 log(sqrt((v - 0.1)^2 + 1) + v - 0.1), at v = 2.4 (a hill that clearly blocks the view) |
| Deep valley or canyon | 15 dB on top of Egli's median | Editorial estimate |
| Scattered trees | 7.9 dB | Weissberger foliage model, L = 1.33 f^0.284 d^0.588 (f in GHz, foliage depth d in m), assuming 30 m of trees in the path |
| Dense forest | 16.0 dB | Weissberger model, assuming 100 m of trees in the path |
| Suburban houses | 10 dB | Editorial estimate |
| Town or city buildings | 20 dB | Editorial estimate; the 10 dB gap to suburban is close to the 8.4 dB gap the Okumura-Hata model gives between its urban and suburban cases at 462 MHz |
| One radio indoors | 12 dB | Editorial estimate; real buildings range from a few dB (wood frame, near a window) to far more (metal, concrete, basements) |
| Handheld against the body | 3 dB per handheld | Editorial estimate; published body-loss measurements at UHF vary widely with grip and position |
| Feedline, per 100 ft | RG-58 12.7 dB, LMR-240 5.4 dB, LMR-400 2.7 dB | LMR: Times Microwave published attenuation tables. RG-58: fitted to its quoted 3.3 dB per 100 ft at 50 MHz and 21.5 dB at 1 GHz |
Antenna gains use common figures: about -3 dBi for a stock handheld antenna, about 0 dBi for a full-size handheld whip, 2.15 dBi for a quarter-wave roof mount, and dBd ratings (3 dB and 6 dB) converted to dBi by adding 2.15, since most vehicle and base antenna makers quote dBd. Pick "Custom gain" if your antenna's sheet says otherwise.
4. Link budget
Received power = transmit power (dBm) + transmit antenna gain + receive antenna gain - feedline losses - body loss - path loss - extra losses. The link works while that stays above the receiver threshold, -116 dBm by default. The reliable range keeps a 10 dB fade margin for signal fluctuation; the best case uses none. Both directions of a two-way conversation are computed and the weaker one sets the range, so a 50 W base talking to a 5 W handheld is limited by the handheld's reply.
5. Solving for distance
Because the loss grows as 40 log(d), the distance where the budget runs out has a closed-form answer. The calculator then caps it at the radio horizon and tells you which limit binds: if the horizon binds, only antenna height helps; if signal strength binds, power, antennas, feedline and terrain all matter. In repeater mode each radio's link to the repeater (467 MHz up, 462 MHz down) is computed the same way, with the repeater's height as one antenna, and the result is a radius around the repeater.
What does the model leave out?
- The actual terrain profile between you and the other radio. A real hill exactly in the way can cut the range to a few hundred yards; a clear view across a valley can stretch it well past these numbers. For a specific path, look at a topographic map.
- Tropospheric ducting and other unusual propagation, which occasionally carries UHF signals far beyond the horizon.
- CB and HF radio. At 27 MHz and below, ground wave and skip behave differently, so CB is outside this model.
- Digital modes, interference and noise from other users, and radio-specific receiver quality beyond the threshold you enter.
The estimate is a median: half of real paths in that class will do better and half worse. Treat it as a planning number, not a guarantee, and test with the radios before you depend on them.
Which FCC limits does it check?
For FRS: 2 W ERP on channels 1-7 and 15-22, 0.5 W ERP on channels 8-14 (47 CFR 95.567), a non-removable antenna (47 CFR 95.587), and no repeaters. For GMRS: 5 W ERP on channels 1-7, 0.5 W ERP on channels 8-14 for hand-held units only, and 50 W transmitter output for mobile, base and repeater stations on the main channels 15-22 (47 CFR 95.1767). ERP is computed as power plus antenna gain minus 2.15 dB minus feedline loss. The calculator flags a setting that exceeds a limit; it does not tell you a setup is legal, which also depends on the radio's FCC certification. Rules apply in the United States only: Europe and many other countries use PMR446 instead, under their own regulators.
Related guides
- Best long-range walkie-talkies: what the range on the box means, and which radios to buy.
- GMRS antenna guide: whip swaps, roof mounts and base antennas, with the height-versus-gain trade-off.
- GMRS repeaters: how to find one, ask for access and program the tones.
- GMRS radio explained: what GMRS is, who needs it and what it costs.
Frequently asked questions
Quick answers to what readers ask us most
How far can walkie-talkies really reach?
Between two people on the ground, most FRS and GMRS handhelds reach well under the number on the box. With this model, two 5 W GMRS handhelds at head height reach 0.5 to 1.0 miles among suburban houses, 0.3 to 0.6 miles on a hilly, wooded trail and 1.8 to 3.2 miles over flat open ground or water. Two license-free FRS radios on open rolling ground reach 0.8 to 1.4 miles.
Why does the box say 36 miles?
Packaging range is a best-case, line-of-sight figure, typically from one high point to another. The calculator reproduces it: put one 5 W handheld 3,000 ft above the other over open ground and the estimate is 44 to 78 miles. Drop both radios back to the ground in a neighborhood and the same radios manage 0.5 to 1.0 miles.
Does a taller antenna or more power add more range?
Both help, and height often costs less. On rolling ground, raising one handheld from 5 ft to 15 ft takes two GMRS handhelds from 1.0 to 1.7 miles reliable range, while ten times the power on both radios (5 W to 50 W) gives 1.7 miles. Height also lifts the radio horizon, which power cannot. See the GMRS antenna guide for the practical options.
How far can GMRS reach through a repeater?
A repeater listens on a 467 MHz input and retransmits on 462 MHz from a tall antenna, so each radio only has to reach the tower. With a 50 W repeater antenna 100 ft up, this model gives a 5 W handheld 5.2 to 9.2 miles from the repeater and a 50 W mobile 14 to 18 miles in rolling, lightly wooded country. How to find and use one is in the GMRS repeater guide.
Is GMRS longer range than FRS?
Somewhat, mainly because GMRS allows more power on channels 15-22, removable antennas, vehicle and base radios, and repeaters. Handheld to handheld on open rolling ground the model gives 0.8 to 1.4 miles for FRS and 1.0 to 1.7 miles for 5 W GMRS. The bigger jump comes from a mobile radio, a better antenna or a repeater. The GMRS vs FRS comparison covers the rules side.
Do I need a license to use these radios?
FRS radios need no license. Transmitting on GMRS needs an FCC GMRS license: no exam, a $35 application fee, a 10-year term, and it covers your immediate family. Ham radios on 2 m and 70 cm need an amateur license, which does require an exam. The GMRS license guide walks through the application.
Does this calculator work for CB radio?
No. CB runs at 27 MHz, where ground wave and occasional skip propagation behave differently from VHF and UHF line-of-sight radio. The model here is built for roughly 40 to 1,000 MHz.