How to convert Wifi signal strength from Quality (percent) to RSSI (dBm)?

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How should I convert Wifi signal strength from a Quality in percentage, usually 0% to 100% into an RSSI value, usually a negative dBm number (i.e. -96db)?

Wifi Signal Strength Percentage to RSSI dBm

Microsoft defines Wifi signal quality in their WLAN_ASSOCIATION_ATTRIBUTES structure as follows:

wlanSignalQuality:

A percentage value that represents the signal quality of the network. WLAN_SIGNAL_QUALITY is of type ULONG. This member contains a value between 0 and 100. A value of 0 implies an actual RSSI signal strength of -100 dbm. A value of 100 implies an actual RSSI signal strength of -50 dbm. You can calculate the RSSI signal strength value for wlanSignalQuality values between 1 and 99 using linear interpolation.

RSSI (or "Radio (Received) Signal Strength Indicator") are in units of 'dB' (decibel) or the similar 'dBm' (dB per milliwatt) (See dB vs. dBm) in which the smaller magnitude negative numbers have the highest signal strength, or quality.


Therefore, the conversion between quality (percentage) and dBm is as follows:

    quality = 2 * (dBm + 100)  where dBm: [-100 to -50]

    dBm = (quality / 2) - 100  where quality: [0 to 100]

Pseudo Code (with example clamping):

    // dBm to Quality:
    if(dBm <= -100)
        quality = 0;
    else if(dBm >= -50)
        quality = 100;
    else
        quality = 2 * (dBm + 100);

    // Quality to dBm:
    if(quality <= 0)
        dBm = -100;
    else if(quality >= 100)
        dBm = -50;
    else
        dBm = (quality / 2) - 100;

Note:

Check the definition of Quality that you are using for your calculations carefully. Also check the range of dB (or dBm). The limits may vary.

Examples:

Medium quality:   50%      ->   -75dBm   = (50 / 2) - 100
Low quality:      -96dBm   ->   8%       = 2 * (-96 + 100)

How can I convert percentage value that represents the signal , How can I convert percentage value that represents the signal quality of the dBm? We found this paragraph in windows documentation; Is this true for all wireless router? A value of 0 implies an actual RSSI signal strength of -100 dbm. respectively? or set "Show" to differential pairs to see St(Diff1,Tline_T3)? or other? Depending on your OS and application, WiFi signal strength is represented either as quality in percentage, or an RSSI value in dBm, i.e. -70db. RSSI is usually expressed in decibels relative to a milliwat (dBm) from zero to -120dBm and the closer it is to zero, the stronger the signal is.

In JS I prefer doing something like:

Math.min(Math.max(2 * (x + 100), 0), 100)

My personal opinion is that it's more elegant way to write it, instead of using if's.

Best dBm Values for Wifi, How does RSSI (dBm) relate to signal quality (percent)?. Depending on your OS and application, WiFi signal strength is represented either as  Wifi Signal Strength Percentage to RSSI dBm. Microsoft defines Wifi signal quality in their WLAN_ASSOCIATION_ATTRIBUTES structure as follows: wlanSignalQuality: A percentage value that represents the signal quality of the network. WLAN_SIGNAL_QUALITY is of type ULONG. This member contains a value between 0 and 100.

From experience:

  1. Less than -50dB (-40, -30 and -20) = 100% of signal strength
  2. From -51 to -55dB= 90%
  3. From -56 to -62dB=80%
  4. From -63 to -65dB=75%

    The below is not good enough for Apple devices

  5. From -66 to 68dB=70%
  6. From -69 to 74dB= 60%
  7. From -75 to 79dB= 50%
  8. From -80 to -83dB=30% Windows laptops can work fine on -80dB however with slower speeds

How does RSSI (dBm) relate to signal quality (percent) ? :: SG FAQ, Depending on your OS and application, WiFi signal strength is represented either as quality in percentage, or an RSSI value in dBm, i.e. -70db. RSSI is usually  Converting Signal Strength Percentage to dBm Values Joe Bardwell, VP of Professional Services Executive Summary WildPackets’ 802.11 wireless LAN packet analyzers, AiroPeek and AiroPeek NX, provide a measurement of RF signal strength represented by a percentage value. The question sometimes arises as to why a percentage

Im glad I found this post cause I was looking for a way to convert the dbm to percentage. Using David's post, I wrote up a quick script in python to calculate the quality percentage.

#!/usr/bin/env python3
import os
import platform

system = platform.system()
if system == 'Linux':
    cmd = "iwconfig wlan0 | grep Signal | /usr/bin/awk '{print $4}' | /usr/bin/cut -d'=' -f2"
elif system == 'Darwin':
    cmd = "/System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport -I | grep CtlRSSI | awk '{ print $NF; }"
else:
    print("Unsupported os: {}".format(system))

dbm = os.popen(cmd).read()
if dbm:
    dbm_num = int(dbm)
    quality = 2 * (dbm_num + 100)
    print("{0} dbm_num = {1}%".format(dbm_num, quality))
else:
    print("Wifi router connection signal strength not found")

In order to get the highest wifi quality from where my computer is located, I moved/rotated my antenna until I received the highest quality. To see real time quality, I ran the above script using:

watch -n0.1 "python getwifiquality.py"

RSSI: How to check RSSI value with NetSpot, Know what a good RSSI level is and how it is related to a signal strength. Signal Strength Indicator is the name for the signal strength of a wireless network environment. Even though RSSI and dBm are different units of measurement they both down the approximate interrelation between RSSI and quality percentage. The GUI uses the term Link quality and Link strength. I read out the RSSI from the AMW007. Is it possible to convert this value to signal strength/quality in %? Is it OK to say that -100 dBm is 0% and -50 dBm is 100% as link quality? And how does Link strength fit in? I now the RSSI is a better indication, but changing the GUI is a difficult task..

From RSSI vs RSS:

RSSI - Received Signal Strength Indicator RSS - Received Signal Strength

RSSI is an indicator and RSS is the real value. Ok, now what do you mean by indicator, indicator mean it can be a relative value and RSSI is always a positive value and there is no unit for the RSSI.

We can say RSSI is for common man to understand. RF values are always told in dBm and the values are negative values most of the time. To make it easy for the people to understand these negative values are converted to positive values through scaling.

Say for example, if the maximum signal strength is 0 dBm and minimum is -100 dBm. We can scale it like as explained. We can put 0 dBm and more (RSS) as 100 RSSI (i. e. maximum RSSI) and -100 dBm (or less) as 0 RSSI (minimum RSS).

Solved: Signal Strength - dBm calculation?, Solved: Signal strength values returned by the WSN nodes seem to Turn off suggestions Is that RSSI percentage value cut off at a certain point or does it span from the entire range of dBm values (-102 to +17)? I understand that the Currently, we have -39 dB representing 100% link quality, and -97  Unusable quality: 8% ~= -96dbDepending on your OS and application, WiFi signal strength is represented either as quality in percentage, or an RSSI value in dBm, i.e. -70db. RSSI is usually expressed in decibels from 0 (zero) to -120db and the closer it is to zero, the stronger the signal is.

Conversion of signal strength in dBm to percentage in WiFi Explorer , Conversion of signal strength in dBm to percentage in WiFi Explorer across this document titled Signal Quality as a Percent for IPW2200. Received Signal Strength Indicator (RSSI) is another option, but Wi-Fi vendors handle it inconsistently and with varying scales. Decibels relative to milliwatt (dBm) avoids these problems, and many manufacturers convert RSSI to dBm anyway, so we’ll cover that measurement.

WiFi Signal Strength Basics, How should I convert Wifi signal strength from a Quality in percentage, usually 0​% to 100% into an RSSI value, usually a negative dBm number (i.e. -96db )?  You can convert milliwatts values to dBm using the formula: P dBm = 10 x log 10 (P mW). In an inverse manner, to convert dDm to milliwatts values you would use: P mW = 10 (P dBm /10). In the context of 802.11 networks, a signal received at -40 dBm (0.0001 mW) would be considered a very strong signal, while a signal received at -80 dBm (0.00000001 mW) would be considered very weak.

Introduction to Wireless Sensor Networks, Since RSSI is handled differently by most WiFi adapters, it's usually converted to dBm to make it consistent and human-readable. mW - milliwatts (1 mW = 0 dBm)​  dBm - Decibels in relation to a milliwatt (usually -30 to -100). Different vendor goes with different way to measure signal strength collected by their APs. I think Meraki APs uses RSSI since I saw positive signal strength values in our data. I saw a document [*] which shows conversion (from RSSI to dBm) for Cisco device as follows: 0 = -113

Comments
  • There is no universally-agreed meaning of 'quality'. Microsoft has one definition, described in the accepted answer, but other software may not use this definition. For example, WiFi Explorer says that -20 dBm is 100%, and even points out that "other tools show percentage values for signal strength that are far off from what you see in WiFi Explorer."
  • Article you point is erroneous because dBm is already a nonlinear logarithmic represent of mW. So this solution is logarithm of logarithm. So we have "signal quality is double logarithm of signal power" - this is nonsense.
  • @imbearr You might be right, but this values were figured by real situation. What's your solution then?
  • I'm prefer to use solution proposed by David Manpearl. This is simple linear convertation, it produce only even values of percent but I think we can't doing something better, because we have only integer dbm value as source.