dBm to Watts Converter
Enter a power level in dBm, watts or milliwatts to convert it to the other two units. Useful for transmitter output, link budgets and RF power measurements.
How to use the dBm to watts calculator
- Pick which unit you have: dBm, watts or milliwatts.
- Enter the value, for example 30 dBm.
- Read the equivalent power in the other two units.
Examples
30 dBm to watts
dbm = 30
1000 mW, 1 W
100 watts to dBm
watts = 100
50 dBm, 100000 mW
Frequently asked questions
What is the dBm to watts formula?
Power in milliwatts is 10 raised to the dBm divided by 10, so mW = 10^(dBm / 10). Divide milliwatts by 1000 to get watts. For example 30 dBm is 1000 mW, which is 1 watt.
How do I convert watts to dBm?
First convert watts to milliwatts by multiplying by 1000, then take dBm = 10 * log10(milliwatts). So 100 watts is 100000 mW, which is 50 dBm.
What is 0 dBm in watts?
0 dBm equals 1 milliwatt, which is 0.001 watts. The dBm scale is referenced to 1 milliwatt, so 0 dBm is exactly that reference power.
Can dBm be negative?
Yes. Negative dBm means power below 1 milliwatt, common for received signals. For example a sensitive receiver might hear a signal at -90 dBm, which is 0.000000001 milliwatts.
Why does adding 3 dB roughly double the power?
Because the scale is logarithmic, every 3 dB increase is about a factor of two in power, and every 10 dB is exactly a factor of ten. So 33 dBm is about twice the power of 30 dBm.
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