About

The unit dBm (decibel-milliwatts) is the industry standard for expressing power in Wi-Fi networks, fiber optics, and Bluetooth devices. Unlike linear units, dBm offers a concise way to represent the huge dynamic range of signal strengths. For instance, a Wi-Fi signal drops by a factor of 100 million between the router and a distant laptop, yet the dBm scale only shifts by roughly 80 points.

This tool converts these logarithmic readings into linear Watts for hardware verification and includes a reference guide to interpret signal quality (e.g., determining if -75 dBm is sufficient for video streaming).

Formulas

Since 0 dBm equals 1 milliwatt (0.001 Watts), the conversion to base Watts requires an offset.

P_(W) = 1W × 10^{((P_dBm − 30) ÷ 10)}

To convert to milliwatts (mW) instead: P_(mW) = 10^{(P_dBm ÷ 10)}.

Reference Data

Signal (dBm)	Quality	Typical Experience
-30	Excellent	Max signal right next to router.
-60	Good	Stable, reliable streaming & VoIP.
-70	Fair	Web surfing works; video may buffer.
-80	Poor	Frequent connection drops.
-90	Dead Zone	Unlikely to connect. Noise floor.

Frequently Asked Questions

Anything above -67 dBm is generally considered good for streaming and reliable use. Once you drop below -70 dBm, performance degrades. Below -80 dBm is usually unusable.

Because wireless signals are extremely weak (much less than 1 milliwatt) by the time they reach the receiver. A negative log value represents a fraction between 0 and 1.

Yes. The 3 dB rule applies here too. If you go from -70 dBm to -67 dBm, the signal power has doubled.

Only if you know the impedance (resistance) of the system. In 50-ohm RF systems, there are direct conversions, but dBm is strictly a measure of power, not voltage.