Six free calculators covering the most common ham radio math — antenna sizing, Ohm's Law, repeater offsets, decibels, and coax loss. All run in your browser, no account needed.
Enter a frequency, get wavelength plus full-wave, half-wave, and quarter-wave antenna lengths in feet and meters.
Solve for voltage, current, resistance, or power. Enter any two values and calculate the other two instantly.
Enter an output frequency, get the correct offset, transmit frequency, and standard CTCSS tone table for your band.
Convert between dB and power/voltage ratios. Calculate antenna gain, feed line loss, and signal path budgets.
Estimate signal loss in common coax types (RG-58, RG-8X, LMR-240, LMR-400) at VHF and UHF frequencies.
Estimate the minimum safe distance from your antenna based on power, frequency, and antenna gain.