milliwatts to dBm

The milliwatt is the unit dBm is defined against, so the reverse conversion is just as direct: 1 mW is exactly 0 dBm, 10 mW is 10 dBm, and 100 mW is 20 dBm. Receiver sensitivity specs, optical power meters, and sensor outputs all report in mW or dBm — and the conversion between them is the definition of the scale itself.

By EnginStack Engineering Team | Verified by engineers, built on NIST metrology standards About →
milliwatts
— dBm
— —

Source: NIST SP 811 and the 1959 yard-and-pound agreement (0.9144 m, 0.45359237 kg). Every decimal place in the factor above is a defined constant, not a measurement.

milliwatts to dBm

dBm = 10·log10(P_mW) is exact, and the conversion matters because equipment picks one unit per context: sensor data sheets quote mW, radio engineers quote dBm, and optical power meters often display both. The practical band for receivers is picowatts (−90 dBm) up through milliwatts — this calculator covers the mW side where the numbers stay readable, and it is the bridge between the lab bench and the link budget.

dBm = 10 × log10(milliwatts)
1 mW = 0 dBm  ·  10 mW = 10 dBm  ·  100 mW = 20 dBm
The conversion is exact by the definition of dBm.

Common milliwatts to dBm Values

milliwattsdBmContext
1 mW—0 dBmThe dBm anchor.
2.5 mW—4 dBmBluetooth Class 2.
10 mW—10 dBmBluetooth Class 1.
100 mW—20 dBmWi-Fi transmit.
1,000 mW—30 dBm1 W — regulatory limit.

Engineering Context

mW-to-dBm is the inverse of dBm to mW, and together they cover the milliwatt band of the electric hub. The watt-scale versions live on dBm to watts and watts to dBm, and the broader power story connects to the energy family.

More: dBm to mW · W to dBm · dBm to W · Electric Hub

Related Unit Converters

Dbm To Mw Watts To Dbm Dbm To Watts Electric Converters

Frequently Asked Questions

How many dBm is 1 milliwatt?

Exactly 0 dBm — the definition of the scale. 10 mW is 10 dBm, 100 mW is 20 dBm, and 1 W (1,000 mW) is 30 dBm.

Why does receiver sensitivity use negative dBm?

Because received signals are tiny — a good receiver hears down to about −90 dBm, which is one picowatt. The dB scale keeps such extreme smallness readable: −90 dBm beats writing 0.000000001 W.

How do I convert mW to dBm by hand?

Count powers of 10: 1 mW = 0 dBm, 10 mW = 10 dBm, 100 mW = 20 dBm. For other values use 10·log10(mW) exactly, or the reverse of 10^(dBm/10).