dBm (deciBel-milliwatts) is a unit of power relative to 1 milliwatt.
dB (deciBels) is a ratio that expresses the relationship between two values of power, voltage, or intensity. It’s also logarithmic.
To convert dBm value to dB, a reference power level must be specified
In the calculator, enter
- dBm value dbm1 and
- Reference value dBm2
The tool will calculate the ratio in dB
🔁 dB to dBm
Formula
dB = dBm1 – dBm2
Example
If
- dBm1 = 40 dBm
- dBm2 = 30 dBm
then,
dBm1 – dBm2 = 10 dB
Note that this is not the difference in power level between the two. Instead it is the ratio of powers which has no units.
- dBm1 = 40 dBm = 10 Watt
- dBm2 = 30 dBm = 1 Watt
The ratio between the two is 10W/1W = 10.
On the log scale it works out to:
10*Log10(10) = 10 dB
Related Calculators
- dBm to Watt
- dBm/Hz to dBm
- Volt to dBm