Coax Cable Loss Calculator
Calculate signal loss in coaxial cables. Enter circuit values to calculate the selected electrical quantity.
Cable Specifications
Electronics guide · Signals, timing, and radio frequency
About Coaxial Cable Loss Calculator
Estimate total coax cable attenuation from a loss rating per 100 units and the cable length. It converts the dB loss into a power percentage remaining, which can help explain how cable length affects a signal path.
Signal and RF calculations connect frequency, period, wavelength, bandwidth, sampling, impedance, and ratios. Results often assume ideal propagation or a simplified signal model; real cables, antennas, clocks, and converters can add losses, tolerances, reflections, and environmental effects.
How to Use This Tool
- 1.Enter the cable's loss rating in dB per 100 units from its datasheet at the operating frequency.
- 2.Choose whether that rating is per 100 meters or per 100 feet and enter the installed cable length on the same basis.
- 3.Calculate total loss and remaining power, then consider connectors and other RF components separately.
Technical Details to Check
1.Frequency and time are linked
For a periodic signal, period is the reciprocal of frequency. Convert prefixes carefully: hertz, kilohertz, megahertz, and gigahertz differ by powers of one thousand.
2.Propagation depends on the medium
Wavelength is related to frequency and propagation speed. A free-space estimate differs from wavelength in a cable or material where the signal travels more slowly.
3.Logarithmic ratios need a reference
Decibels and related units describe ratios, often with a stated reference such as dBm. Check whether the tool is converting power, voltage, or a normalized ratio before using the value.
4.Sampling is not reconstruction quality
A sampling condition can help assess whether a signal's frequency content is representable, but real filters, clock jitter, noise, and system bandwidth also affect sampled data.
How the Calculation Works
Total attenuation in dB = loss per 100 units × length ÷ 100. Remaining power fraction = 10^(−total dB/10), displayed as a percent. Cable loss changes with frequency, cable type, temperature, and installation condition, so use a datasheet value for the relevant frequency.
Worked Example
A cable rated at 5 dB per 100 feet used for 25 feet has an estimated loss of 1.25 dB before connector losses.
Where This Tool Can Help
Estimate signal power reduction for a cable run and compare shorter routes or lower-loss cable options.
Converting signal units
Move between frequency, time, wavelength, or power representations while keeping the source unit and reference clear.
Checking a communications setup
Estimate baud timing, clock tolerance, or signal ratios, then compare the result with the transceiver and protocol requirements.
Planning an RF or antenna estimate
Use a frequency-based result as a starting point and account separately for material, antenna geometry, matching, and the surrounding environment.
Reviewing sampled signals
Check a theoretical sampling relationship before testing the actual signal path, filters, converter limits, and clock quality.
Tips for More Reliable Results
- Write down the frequency, time, impedance, and reference units before entering a value.
- Check whether the formula assumes free-space propagation, ideal components, or a matched load.
- For dB values, identify the reference and whether the underlying quantity is power or amplitude.
- Compare theoretical results with datasheets, measured behavior, and the operating frequency range.
Limitations and Assumptions
The calculation assumes loss scales linearly with length and does not include connectors, adapters, mismatch, bends, or frequency changes along the run. The power percentage is not the same as voltage percentage. Measure a real RF path when performance matters.
Signal calculations describe a model, not a complete measurement of a physical system. Propagation medium, component tolerance, noise, impedance mismatch, bandwidth, and instrument limitations may not be represented by the inputs.
Frequently Asked Questions
What does 3 dB loss mean?
It is roughly half the power remaining under an ideal matched-system interpretation.
Does cable loss stay constant at every frequency?
No. Attenuation generally depends on frequency and the cable's construction.
Does this calculate voltage loss?
It converts dB to a power ratio; voltage ratio uses a different dB relationship under equal impedance.
Is wavelength always the free-space value?
No. The medium changes propagation speed, so a cable or material can have a shorter wavelength than free space.
Does a sampling calculation guarantee a clean digital signal?
No. Filtering, noise, clock accuracy, converter performance, and signal bandwidth also matter.