Keep units explicit
Use the converter for quick engineering calculations and double-check the unit shown beside every result before using it in a build.
Unit Converter
Enter a value on the left; results appear on the right. Fields do not fight each other.
Power
Watts—
dBm—
dBW—
Length
Metres—
Feet—
Inches—
Gain
dBi—
dBd—
dBi = dBd + 2.15
Practical notes
dBm is power relative to 1 mW. 0 dBm = 1 mW, 30 dBm = 1 W, 50 dBm = 100 W.
dBi vs dBd – dBi is relative to isotropic; dBd is relative to a half-wave dipole. Difference is 2.15 dB.
Length conversions are exact. Antenna dimensions still need pruning for velocity factor and environment.
Avoid rounding during intermediate steps
Unit conversion itself is deterministic, but rounding can become significant when a converted value is later used in a sensitive RF calculation.
Check the final unit before use
Keep full precision through intermediate calculations and round only the final displayed result.
Use the conversion as an input check
Unit conversion is simple mathematically but surprisingly easy to get wrong when RF work mixes watts, dBm, gain, length and frequency units. This converter keeps common amateur-radio quantities together so that values can be moved between practical units without repeatedly rebuilding formulas. Watts and dBm require a power reference, while dB values represent ratios rather than absolute power. Length conversions are straightforward, but antenna calculations still depend on the units expected by the underlying formula. For example, entering metres where a calculator expects feet can produce a result that looks plausible while being badly wrong. Treat every converted value as an input check: confirm the unit displayed beside the field before using it in another calculation. When comparing equipment specifications, also check whether a manufacturer quotes peak, average or RMS values. A clean unit chain is one of the easiest ways to avoid otherwise invisible RF calculation errors.