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Calcimator

RF Exposure Calculator

Calculate power density at distance for FCC RF exposure compliance. Checks controlled and uncontrolled environment MPE limits.

Inputs

W
dBi
m
MHz
%

Results

Power Density

0.07057 mW/cm²

% of Uncontrolled Limit

35.28 %

Uncontrolled compliant

Yes

Min Safe Distance (Uncontrolled)

1.78 m

≈ 12 smartphones

MPE Limit (Controlled)1 mW/cm²
MPE Limit (Uncontrolled)0.2 mW/cm²
% of Controlled Limit7.06 %
Controlled compliantYes
Average ERP79.81 W
How to Use This Calculator
  1. Enter transmitter output power (W) and antenna gain (dBd or dBi).
  2. Set the distance from the antenna to the nearest person (meters) and operating frequency (MHz).
  3. Enter your duty cycle (%) — the fraction of time actually transmitting.
  4. Review power density (mW/cm²) and compare to FCC MPE limits for controlled and uncontrolled environments.
  5. Ensure you are below 100% of the uncontrolled MPE limit for general public areas.

How the result changes with Distance to Person

Distance to PersonPower Density% of Uncontrolled LimitUncontrolled compliant
100.00635 mW/cm²3.18 %Yes
350.00052 mW/cm²0.26 %Yes
650.00015 mW/cm²0.08 %Yes
900.00008 mW/cm²0.04 %Yes

What each input means

Transmitter Power
Transmitter output power in watts (PEP for SSB)
Antenna Gain
Antenna gain in direction of exposure point
Distance to Person
Distance from antenna to nearest person in meters
Frequency
Operating frequency in MHz (different limits by frequency band)
Duty Cycle
Average duty cycle (SSB voice ~40%, FM ~100%, CW ~50%, digital ~100%)

How this is calculated

Formula

S = (P × G × D%) / (4πd²); FCC OET Bulletin 65

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    Transmitter Power = 100, Antenna Gain = 3, Distance to Person = 3, Frequency = 146 = 5 input(s) provided
  2. Calculate Power Density
    Power Density
    0.07057 = 0.07057
  3. Calculate % of Uncontrolled Limit
    % of Uncontrolled Limit
    35.28 = 35.28
  4. Calculate Uncontrolled compliant
    Uncontrolled compliant
    Yes = Yes
  5. Calculate MPE Limit
    MPE Limit
    1 = 1
  6. Calculate MPE Limit
    MPE Limit
    0.2 = 0.2

Engine last updated . Checked against 2 independently-derived tests — how we verify calculators.

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