Loss rises with frequency, so the same cable run that looks fine on HF may become noticeably worse on VHF or UHF. That matters even more on weak-signal work, long runs, and portable stations where every dB counts. Higher-frequency operation makes cheap or undersized coax more expensive in performance.
Coax Loss Calculator
Estimate feedline loss, delivered power, and efficiency for common coax types across amateur bands. Use it to compare cables before you buy or before you commit to a long run.
Calculate loss
Choose a cable, band, length, and transmitter power to estimate line performance.
Results
LMR-400 · 100 ft · 160m
Total loss
0 dB
Efficiency
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Power to antenna
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Power lost
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Power distribution
Comparison table
Loss values in dB per 100 feet at common frequencies.
Low ≤2 dB
Moderate 2-5
High 5-10
Very high 10+
| Cable Type | Diameter | 30m | 6m | 2m | 70cm | 23cm | Notes |
|---|---|---|---|---|---|---|---|
| RG-58/U | 0.195" | 1.4 | 3.3 | 5.8 | 11.0 | 20.5 | Cheap, high loss, avoid for VHF/UHF |
| RG-316 | 0.100" | 2.8 | 5.4 | 9.2 | 16.5 | 29.3 | Tiny, flexible pigtail coax; keep runs short |
| RG-8X | 0.242" | 1.2 | 2.8 | 5.0 | 9.5 | 17.5 | Mini-8, flexible, moderate loss |
| RG-213 | 0.405" | 0.7 | 1.6 | 2.9 | 5.5 | 10.5 | Standard quality, good for HF |
| RG-8 | 0.405" | 0.6 | 1.5 | 2.7 | 5.2 | 9.8 | Better quality than RG-213 |
| LMR-195 | 0.195" | 1.2 | 2.7 | 4.9 | 9.0 | 16.9 | Small, flexible, low-loss alternative to RG-58 |
| LMR-240 | 0.240" | 0.9 | 2.0 | 3.7 | 6.9 | 13.0 | Better than RG-8X, flexible |
| LMR-400 | 0.405" | 0.4 | 0.9 | 1.7 | 3.3 | 6.6 | Excellent all-around choice |
| LMR-600 | 0.590" | 0.3 | 0.7 | 1.3 | 2.5 | 4.9 | Very low loss, heavier/stiffer |
| LDF4-50A | 0.630" | 0.2 | 0.5 | 0.9 | 1.8 | 3.6 | Hardline, commercial grade |
| LDF5-50A | 0.875" | 0.1 | 0.3 | 0.6 | 1.2 | 2.5 | Hardline, minimum loss |
| Belden 9913 | 0.405" | 0.4 | 1.0 | 1.9 | 3.8 | 7.5 | Popular low-loss choice |
Why loss matters more on VHF, UHF, and longer runs
Feedline loss becomes more visible as frequency and cable length rise. A modest HF run may be acceptable with average coax, while the same cable choice becomes a real station penalty on 2 meters, 70 centimeters, or weak-signal work. That is why the best coax decision depends on the actual band plan, not just price or convenience.
How coax choice affects the whole station
Cable is not separate from the antenna system. The wrong coax can erase gains you expected from a better radiator or a cleaner deployment. After checking feedline loss, compare the build path in Antenna Designer and confirm whether the physical layout still makes sense in Wire Deployments before you commit to the install.
Coax loss FAQ
Check it before you buy cable, before you bury or route a permanent run, and before you finalize a portable field setup. A quick loss estimate can change whether you shorten the path, choose better coax, or adjust the band plan. It is much easier to change the design before the cable is already in place.
No. Feedline loss is only one part of the station. Antenna efficiency, matching, connectors, common-mode issues, installation quality, and the surrounding environment all affect results too. This page isolates the cable piece so you can make a better feedline decision while keeping the rest of the system in view.