Coaxial cable attenuation calculator

Estimate how much signal a coax run loses. Enter the cable length in metres or feet and the operating frequency — the calculator either uses your datasheet loss per metre or estimates it from frequency, then shows the total dB loss and the share of signal power that arrives.

Cable run

Cable length

Length unit

32.8 ft

Frequency & loss per metre

Frequency

Loss per metre rises with frequency.

Datasheet loss (optional)

dB per metre at your frequency — or pick a cable below

Common cable types

Attenuation per metre: 0.640dB/m
Total run attenuation: 6.40dB
Signal power remaining: 22.9%

The estimate follows α ≈ 0.0018·√f + 0.00023·f (f in MHz) — a generic model. Use the datasheet figure for your exact cable type when planning a real link budget.

Does a preamp make sense?

With an inline amplifier gain of your value:

Net loss after gain: --dB

Build the link right

The connectors matter as much as the cable: RF connectors, coaxial connectors and antenna connectors each add a small fixed loss and must match the cable impedance.

Frequently asked questions

How much signal does coax lose per metre?

Total loss is simply attenuation per metre × length. At 2.4 GHz the built-in generic estimate is about 0.64 dB/m (α ≈ 0.0018·√f + 0.00023·f with f in MHz), so a 10 m run loses roughly 6.4 dB — about 77% of the signal power. Real cable datasheets give the exact figure at your frequency, and low-loss types are far better.

Why does coax attenuation increase with frequency?

Skin effect and dielectric losses grow with frequency, which is why datasheets list loss at specific frequencies and the calculator interpolates log-log between them. For example RG-58 loses about 4.9 dB per 100 ft at 100 MHz but 17.4 dB per 100 ft at 1 GHz — more than three times as much.

What is a typical loss budget for a Wi-Fi antenna run?

At 2.4 GHz a low-loss cable like LMR-400 interpolates to about 0.22 dB/m (roughly 2.2 dB per 10 m), while RG-58 runs about 0.95 dB/m (roughly 9.5 dB per 10 m). Subtract the run loss and connector loss from your link budget before deciding whether a preamp makes sense.

How it works

Total loss is simply A = loss-per-metre × length. The per-metre figure is strongly frequency-dependent: the built-in estimate follows a generic α ≈ 0.0018·√f + 0.00023·f (dB/m, f in MHz) model. Real link budgets use the datasheet attenuation at your exact frequency — the estimate is an orientation, not a spec.

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