Radiolabs - Wifi Range Calculator
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WiFi Range Calculator

Calculating your 802.11 power output.

Use this calculator to walk through all the factors that make up your Total Power Output. The Total Power Output is the the total power being output from your wireless system and is the sum of:

  • Radio Transmit Power
  • -Less - cables and connectors losses
  • Antenna gain
Enter one parameter in each column (or leave blank) depending on what you know and the calculator will supply the appropriate conversions automatically. Up to 2 decimal places may be entered as 0.xx or .xx.

Note: Connector loss is generally small UNLESS you've got lots of 'em in which case you are probably in trouble anyway, or your cable is VERY short. Just leave the line blank if you are feeling lazy.

Radio and Antenna    

Transmit Power
(This can be located on the specification sheet from your wireless system)

Antenna Gain
(Select a RadioLabs antenna from our product page and enter the antenna gain)


 dB(i)  dB
Cable Loss    
Cable Properties
(per 100 ft or m)
Cable Length  
 dB (100 ft)
 dB (100 m)

Connector Loss    
Frequency in MHz No. of Connectors  
 MHz.  No.  dB
Free Space Loss

Loss of power over distance (assuming no FRESNEL Effect and nothing in the way). This a very idealised calculation and in practice everything interferes with the signal but it will give you a reasonable approximation of the actual loss over distance.

Enter the system Frequency in MHz and the distance in either Kilometers (Km) or Miles below and then click the 'Calculate' button. 1 GHz = 1000 MHz e.g. 2400 = 2.4 GHz.

Frequency Distance   Result
 MHz  Km
Fresnel Zones

Defines how much clearance you need (yes you need more than simple Line-of-Sight) and for longer links > 3 Km (2 miles) whether you may have a ground clearance problem from our friendly planet. For more info on M. Fresnel and his theories go here.

Enter the Total link distance (in Miles or Kilometers), if you do not enter an Obstacle distance (in Miles or Kilometers) the calculator will use the mid-point for all calculations (Note: assumes antennas at same height). Finally enter the system Frequency in MHz and then click the 'Calculate' button. 1 GHz = 1000 MHz e.g. 2400 = 2.4 GHz.

The calculator will generate the radius of the 1st Fresnel zone only (at the obstable point or the mid-point), the 60% (no obstacle) radius and the height of the earth curvature at the mid-point of the Total link distance.

Total Link Obstacle Distance 1st Fresnel Zone Radius


Frequency   60% No Obstacle Radius
 MHz    m  ft
  Earth Height (mid-point)
     m  ft
System Performance

This calculator will give you one of three answers:

  1. If you leave distance blank it will apply the defined SAD factor (or default to 30%) to the Operating Margin and supply the max. distance (in Km and Miles) at which the Margin operates.
  2. If you enter the distance it will calculate the Operating Margin and the SAD factor.
  3. If you enter distance but leave RX or TX antenna gain (or both) blank it will apply the chosen SAD factor (or default it to 30% if none supplied) and generate the required antenna power. If both are left blank it will calculate a symmetrical antenna gain.
To RESET any parameter above just set to BLANK before clicking 'Calculate'

Notes: RX Sensitivity is ALWAYS expressed as a negative dBm (- dBm) and is the lowest power of signal your radio can handle. Its buried somewhere in your radio spec and will be typically in the range of -80 to -110 dBm. Don't guess or 'fudge' this number.

Frequency Distance   Result
 MHz  Km
TX Power TX Cable TX Antenna  
 dBm  dB  dB
RX Sensitivity RX Cable RX Antenna  
 dBm  dB  dB  dB
Margin RX Power SAD Factor Theoretical Margin
 dBm  %  dB
milliWatts to dBm (and vice versa)

Power in milliWatts to dBm (and vice versa) . Enter the 'Transmit Power' (A or G above) in milliWatts OR the 'Power Ratio' in dBm and click the appropriate 'Calculate' button. 1 Watt = 1000 milliWatts.

Transmit Power   Result
mW  dBm
Power Ratio   Result
 dBm  mW



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