Decibel milliwatts is a wireless power measurement that takes the transmitter's power and divides it by one million. This number is then subtracted from the receiver chip or device receiving the signal transmitted by a router or access point. The result will show how much energy is received over a Wi-Fi connection. The lower the dBm value, the higher the energy received. By using dBm, you can measure how much of your Wi-Fi signal is being absorbed by a room or an object in that location. Some calculators will do this for you automatically when given the information needed.
Calculating dBm Step-by-Step
1) To find the dBm value for a Wi-Fi router or access point, you will need to know the output power of the transmitter in milliwatts. This can be found from either the manufacturer's specs or by looking at your setup software. Most wireless routers and access points have a factory maximum output setting that you can find on their product page on Amazon or Best Buy's website. If you cannot find this information try using Google to search for "<router name> manual pdf" and look through the document for "maximum output power."
2) Find out what channel your wireless network is broadcasting on - There are 11 channels in total so if you have a dual-band router chances are there are two separate channels one 2.4GHz and one 5 GHz.
3) To calculate dBm, plug the numbers into the following equation: Output Power (dBm)= Transmitter Power (milliwatts)/10 + 30
How to Measure Received Signal Strength in
If you do not want to use a calculator and just want to try out your signal with your phone, there is an app for Android and iPhone that lets you see how much power you are receiving from a wireless router or access point. It's called InstaWifi and when installed will allow you to identify the network name (SSID), channel, distance in meters, and received signal strength in dBm with a simple graph. To find the dBm value, look at the top of the "dB" column on the right side after loading up all nearby networks.
Once you have calculated your wireless device's received signal strength rating, you can then adjust where it sits in a room or near an object in the home to increase signal strength. For example, if you have calculated that your received signal is -45dBm at one part of your house or office and -55dBm somewhere else adjust your router accordingly.
The closer you get to 0 (zero), the better for wireless devices. Between -50dBM and -100dBM should be sufficient for managing traffic over Wi-Fi networks. Any other number will cause connection issues like slow speeds or dropped connections while browsing or streaming content. If you find that you are getting a bad signal while moving around near your router then chances are something is interfering with its transmission, such as metal objects, microwaves, walls, etc if you're looking for more information about locating sources of interference read this article.
*Caution: If you are trying to boost signals around your house using an amplifier avoid using one with more than 15dBm output power as anything higher will make the wireless network too powerful for most home routers and result in unstable connections. To boost signal strength without amplifiers, try purchasing high-gain antennas or move your router/access point to a new location to increase range.
Getting a Poor Signal? Get Rid of Obstacle
Walls, furniture, and other obstacles can block a device's wireless signal. There are some steps you can take to get rid of interference problems in your home or offices like moving WiFi routers or access points to the center of the building (ideally high up), away from physical obstructions like walls, cabinets, and pillars. Every surface in an area can block or reflect wireless signals, so you may need to experiment with where the signal is more reliable.
For example; A 2.4 GHz access point placed in a bedroom will usually give good results at close range (a few meters). However, as you move away from it and out into adjoining rooms like the living room and kitchen, though, you might notice that the signal level has dropped considerably.
2.4 GHz is used in homes because it can travel further (and through walls) than 5GHz which provides better speeds but a shorter range. However, if your house is shaped like a box with lots of rooms and/or pillars in the way 2.
Your wireless router's power output is measured in milliwatts (mW) this will determine how far your signal goes, but it isn't the only factor. The distance between your router and the wireless device you are testing will affect the strength of the signal you get back. We also have to consider physical obstructions like walls, floors, and ceilings that can block a signal's path. Fortunately, there is a simple rule-of-thumb you can use to test for a good location if you have multiple floors in your home or office building.
Place the router on the ground floor and walk up or down from it until you notice a reduction in WiFi strength, note this distance as the maximum reach of your router's wireless signal. In my house I found that the WiFi strength from a TP-Link AC1200 was -30dBm at the recommended location and between -50dBm to -70dBm throughout all other areas.