Free-space RF Link Budget Calculator

How to use Free-space RF Link Budget Calculator

Free-space loss is20log10(4πdf/c), with c=299792458m/s. Add entered transmitter dBm and antenna dBi, subtract path/other dB losses, then compare the received dBm with your threshold.

1. Enter frequency (hz), distance (m), transmitter power (dbm), transmit antenna gain (dbi), receive antenna gain (dbi), other losses (db), user receive threshold (dbm).
2. Choose the stated convention and check the units and supported model.
3. Calculate, inspect the result, then copy or download it.

Good to know

• Positive frequencyHz/distance meters;4πdf/c≥1 is required but does not establish the far-field assumption. No terrain, multipath, legal transmit limit, radio database or coverage guarantee.
• Runs locally. Text/JSON fields are capped at30,000 characters; stricter page-specific and numeric-string limits also apply. Numeric inputs are bounded to magnitude1e15 and nonzero magnitude at least1e-100 unless an exact-string mode states otherwise. Approximate summaries use12 significant digits; CSV numeric cells retain the complete stored value and potentially formula-like string cells gain a protective apostrophe; unsupported, non-finite or detected underflow states return an error.