Fresnel Zone Radius Calculator
Calculate first-Fresnel-zone radius at an entered point between two radio endpoints.
YOUR CALCULATION
Result
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Calculation steps
Work through one step at a time or reveal the complete calculation. The steps use your current inputs.
How to calculate
Convert frequency to vacuum wavelength and use the two straight-line endpoint distances in the first-zone approximation.
r1=√(λ d1 d2/(d1+d2)); displayed fraction=r1×percent/100
Worked example
At the midpoint of a 10 km link at 2.4 GHz, first-zone radius is about 17.6715536 m and 60% radius about 10.6029322 m.
Assumptions and input details
Distances are positive line-of-sight path segments. Small-angle geometric approximation; terrain, Earth curvature, refraction, obstacles and actual link availability are excluded. The entered fraction is not a universal clearance recommendation.
Unit definitions
Unit selection is independent of language. Each selector contains only units for its physical quantity. Calculations use defined base units internally.
Choose from 23 length definitions, including explicitly labelled regional measures. Area conversions square the length factor; geometric volumes cube it.
Regional measures are not interchangeable merely because their names look similar. This is a documented selection, not a claim to include every historical unit.
SI prefixes are explicit: for example, milli means one thousandth, micro one millionth and kilo one thousand. Changing a unit changes the interpretation of the entered number.
NIST measurement tables · Japanese traditional units · Mainland China and Hong Kong unit distinctions
Using this calculator
Can I enter my own problem?
Yes. Replace the example values with your own inputs. The result, calculation steps, tables and applicable diagrams update from those inputs. Blank or invalid values clear the result; example values are never silently substituted for missing inputs.
Are the results exact?
Results use floating-point arithmetic and displayed rounding. Read the formula, assumptions and any stated data precision before interpreting the result.
Is my input uploaded?
The calculation runs in your browser. No account, file upload or external AI service is required. Inputs are not saved between page reloads.
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