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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.
EIRP (dBm) = Pt(dBm) + Gt(dBi) − Lcable(dB); EIRP(W) = Pt × GlinearThe calculation requires: TX Power, Antenna Gain, Cable Loss. 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.
When a formula combines multiple measurements, all inputs must use compatible units. Convert everything to the same system (metric or imperial) before calculating.
Calculate Effective Isotropic Radiated Power from TX power and antenna gain. Free online ham radio calculator with instant, accurate results. It applies the calculation formula (EIRP (dBm) = Pt(dBm) + Gt(dBi) − Lcable(dB); EIRP(W) = Pt × Glinear). For example: 100 w, 8 dbi, 1.5 db loss — A typical use case demonstrating the calculator with representative values.