Ham radio calculators & tools
Free, fast calculators for the shack. No sign-up, nothing to install — and every tool explains the formula it uses.
Antenna length calculator
Half-wave dipole, quarter-wave vertical and full-wave loop lengths for any frequency, in feet and metres.
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SWR & mismatch loss calculator
Turn SWR into return loss, reflected power and mismatch loss — or work out SWR from forward and reflected watts.
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Grid square locator
Find your Maidenhead grid square from latitude and longitude (or your device location), and decode any grid.
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Also live on HamPost: today's HF propagation conditions and real-time DX cluster spots.