Coax Cable Loss Calculator
How much of your signal survives the feed line, for every popular LMR, RG and hardline cable.
- Manufacturer datasheet data
- Kp 1.7
- Solar flux 106
- 07:39 UTC
Compare cables at this length and frequency
Loss vs frequency
About this tool
Where the numbers come from
Attenuation comes from each manufacturer's datasheet. Where the manufacturer publishes its loss formula (Times Microwave LMR: dB per 100 ft = k1·√f + k2·f) that is used directly; otherwise the published table is interpolated on a log-log scale. Values are for new cable at room temperature; old, wet or kinked cable loses more. RG-9/U isn't listed because no current manufacturer datasheet is available; RG-213 is its closest modern equivalent.
SWR and connectors
A mismatched antenna reflects power back down the line, and the line loses some of it on every trip. The extra loss uses the standard ARRL formula and grows quickly on lossy cable. Each connector is counted as about 0.1 dB, a typical figure for good N or PL-259 connectors at VHF/UHF; poor connectors and adapters can be much worse at microwave frequencies.
Rule of thumb
Every 3 dB of loss halves your power, on transmit and on receive. On receive the loss comes straight off your signal-to-noise ratio unless a preamp is mounted at the antenna, which is why short runs of thick cable (or a mast-mounted LNA) matter so much for ADS-B, satellites and microwave.