When you install a WiFi network in your home, you might want to understand its range and answer questions like:
If I install my Wi-Fi router in the basement, will I be able to
- connect to my home network from the attic?
- connect to the router from my back yard?
This tool can be used to answer these questions.
Contents
Calculator
You will need to input:
- Distance from the Wireless LAN Access point or Router in meters or feet
- Number of walls that separate the router from your laptop or tablet
The calculator will output the RSSI in dBm. This RSSI value can be used to understand the quality of your Wi-Fi connection. The higher the RSSI the better and faster your connection to the internet.
🛜 Plan your wireless network using the Wi-Fi Access Point Calculator
What does RSSI in a Wi-Fi network mean?
RSSI stands for Received Signal Strength Indicator. The further away the device is from the Wi-Fi hotspot, the lower the value of RSSI. Here is a table that tells you what the level needs to be for good performance.
| RSSI (dBm) | Quality | What does it mean? |
| -30 to -20 | Excellent | No issues |
| -50 to -31 | Very good | No issues |
| -65 to -51 | Good | Adequate for streaming although you might have issues with interference in apartment buildings |
| -90 to -66 | Poor | Might work but will have issues with streaming and dropped connection |
| Less than -90 | Very poor | The network cannot be used |
Levels in the first column will result in the performance level indicated in the second column. The impact is specified in the third column.
Note: In this case we have taken RSSI to be equal to dBm. Some vendors have a different definition of RSSI – use this calculator to find the equivalent dBm value.
What is dBm?
dBm is the power in dB referenced to one milliwatt. It is commonly used in wireless systems like Wi-Fi, 4G and 5G. Here are a couple of useful calculators to convert from:
The dBm to percent calculator gives an intuitive feel for how good the Wi-Fi signal is
What impacts RSSI?
Note that the received RSSI value in Wi-Fi systems is typically a negative number. Although sometimes in practice people will refer to it without the sign.
A consumer Wi-Fi access point typically transmits +20 dBm and the strength decreases exponentially with distance. Floors and walls also attenuate the signal level.
How to improve RSSI?
To improve signal levels, reduce the number of obstructions and the distance between the Wi-Fi router and any client devices.
In laptops and Wi-Fi devices, the antennas are embedded within the device and the customer has no access to them. In general however, antennas have a significant impact on performance. In the case of laptops there is the option to use a USB Wi-Fi dongle with an external antenna. This will improve performance significantly.
What is the maximum range of a Wi-Fi network?
Based on the table above, an RSSI value of lower than -90 dBm makes the network unusable. The maximum range based on the calculator is 60 meters or around 200 feet.
At distances greater than this you will not be able to connect to your Wi-Fi network. Note that if there are any walls or other obstructions the range will be reduced even further and will be less than 200 feet.
RSSI vs Distance
This table shows the values of RSSI versus distance from a Wi-Fi hotspot. We’ve picked threshold values as per the table above for the different performance levels
| RSSI (dBm) | Performance | Distance (ft) | Distance (m) |
| -30 | Excellent | 6 | 2 |
| -50 | Very good | 18 | 6 |
| -65 | Good | 40 | 12 |
| -90 | Poor | 200 | 60 |
Note that these values are calculated indoors with no walls or floors between the router and the client device (laptop for example). Walls or floors will reduce the distance further.
RSSI to Internet Speed
This post explains how RSSI translates to Internet Speed (Mbps)
Interference to Bluetooth
Positioning your laptop close to a Wi-Fi access point will maximize RSSI. However it will interfere with the operation of other wireless devices such as Bluetooth that share the same frequency band.
While you can’t see the invisible RF signals that cause interference (without an instrument such as a spectrum analyzer), you will notice that the Bluetooth mouse or keyboard starts to lag or disconnect periodically.
The table above shows that there is a range of signal level (-30 to -50 dBm) for which the performance is quite good.
As a result, it benefits all wireless systems to move the Wi-Fi AP further away from devices that connect to it.
References
[1] Modeling Signal Attenuation in IEEE 802.11 Wireless LANs – Vol. 1 by Daniel B. Faria