WiFi Signal Strength Calculator

dBm is a logarithmic unit expressing power relative to one milliwatt. For WiFi, received signal strength (RSSI) is always a negative number: the closer to zero, the stronger the signal. A signal of -30 dBm is excellent and typically only achievable very close to the router. -50 dBm is considered excellent for most applications. -60 dBm is good for streaming video. -70 dBm is fair and suitable for web browsing. -80 dBm is poor and may cause dropped connections. Below -80 dBm is generally unusable for reliable communication.

Higher frequency radio waves experience greater free-space path loss over the same distance than lower frequency waves. The free-space path loss formula shows that loss increases by 20 dB for every decade of frequency. 5 GHz is roughly twice the frequency of 2.4 GHz, which means approximately 6 dB more path loss at the same distance. In practical terms, 5 GHz has about 20 to 30% less range than 2.4 GHz from the same router, but it offers more available channels and faster maximum speeds when you are within range.

This calculator uses the free-space path loss model, which assumes no obstructions. In real indoor environments, walls, floors, furniture, and other obstacles add signal attenuation on top of the free-space loss. A typical interior plasterboard wall adds 3 to 5 dB of attenuation. A concrete or brick wall adds 10 to 15 dB. A floor or ceiling between levels adds 10 to 20 dB. To estimate practical indoor range, subtract these additional losses from the calculated received signal level. Alternatively, use a WiFi analyzer app to measure actual RSSI at specific locations in your building.

RSSI (Received Signal Strength Indicator) is a relative scale used by WiFi chipset manufacturers to represent signal strength. Different vendors use different RSSI scales (commonly 0 to 100, or 0 to 255), so RSSI values are not directly comparable between devices. Most operating systems and WiFi analyzer tools convert RSSI to dBm for a standardised reading. This calculator uses dBm directly, which is the universally comparable unit for received signal power.

A mesh network uses multiple access points that communicate with each other to create seamless coverage across a large area. It is the preferred solution when a single router cannot cover your space, when there are thick walls or multiple floors, or when you need consistent signal in specific rooms far from the router. Unlike WiFi extenders or repeaters, mesh nodes use dedicated backhaul channels to avoid the bandwidth halving that affects traditional repeaters. Mesh systems are particularly effective when the inter-node links can use 5 GHz or a wired backhaul.