Tools you might need next
Calculate half-wave dipole and quarter-wave vertical antenna element length from frequency. Includes velocity factor correction for wire type.
Calculate Standing Wave Ratio from forward and reflected power readings. Convert SWR to return loss and reflected power percentage.
Calculate coaxial cable RF signal loss in dB from cable type, run length, and frequency. Estimate transmit power delivered to your antenna.
This tool applies a standard formula from the relevant domain. The computation is deterministic — given the same inputs, the result is always identical. The formula accounts for the primary variables that determine the output.
Loss (dB) = (attenuation/100ft) × (length/100ft) × √f_factorThe calculation requires: Cable Length, Loss per 100 ft @ ref freq, Operating Frequency. Each parameter contributes to the final result according to the formula above. Accuracy depends on the precision of your input measurements.
Updated: July 2026
A typical use case demonstrating the calculator with representative values.
→ Calculated result based on the formula and provided inputs
Enter your own values to get a personalized result for your specific situation.
→ Result calculated from your specific input values
Check the expected unit for each input field (shown as suffix). Converting between imperial and metric units before entering values prevents calculation errors.
Ensure denominator values (divisors) are non-zero. The calculator validates this, but understanding which fields cannot be zero helps interpret results correctly.
Estimate coax cable attenuation at frequency and length. Free online ham radio calculator with instant, accurate results. It applies the calculation formula (Loss (dB) = (attenuation/100ft) × (length/100ft) × √f_factor). For example: 100 ft lmr-400 at 146 mhz — A typical use case demonstrating the calculator with representative values.