Ham radio calculators & tools
Free, no-signup calculators for antennas, coax, SWR, repeater offsets, range, power, grid squares, and license study — each works without JavaScript and links to the gear it recommends.
Antenna Length CalculatorEnter your operating frequency in MHz to get a starting antenna length. A half-wave dipole is 468 / f_MHz feet total (each…Coax Loss CalculatorCoax loss grows with cable length and frequency. Loss in dB equals length divided by 100, times the cable's loss per 100…Handheld Radio ComparisonThis comparator lets you line up handheld ham radios (HTs) side by side on the specs beginners actually use: transmit power, battery…Repeater Offset CalculatorEnter the repeater's published (output) frequency and this calculator applies the standard US offset to show your transmit (input) frequency: −100 kHz…License Study PlannerEnter your target exam date and how many hours you can study each week, and the planner spreads the 2026-2030 Technician question…SWR / Return Loss CalculatorSWR (standing wave ratio) measures how well your antenna matches your radio. Below 1.5:1 is excellent, up to 2:1 is fine for…Radio Range CalculatorRadio range on VHF/UHF is mostly line-of-sight, set by antenna height. The radio horizon in miles is about 1.415 times the square…dBm ↔ Watts ConverterTo convert dBm to watts, first find milliwatts with P(mW) = 10^(dBm/10), then divide by 1000 for watts. Going the other way,…Grid Square LocatorA grid square is your location coded in the Maidenhead system, like FN31pr. It compresses latitude and longitude into a short string…