dBm to Watt Converter
Convert RF power between dBm, milliwatts, and watts in either direction — the unit behind every transmit-power spec, antenna gain, and link budget.
Speak the RF power language
Datasheets quote transmit power in dBm, amplifiers in watts, and receiver sensitivity in negative dBm — and a link budget needs them all on one scale. Converting fluently between dBm and watts is the small skill that keeps a power calculation from going wrong by a factor of ten, and it makes the logarithmic feel of RF power second nature.
Carry the converted power into the RF Link Budget Calculator, turn a channel's signal-to-noise ratio into throughput with the Shannon Channel Capacity Calculator, and work out the ideal path loss with the Free-Space Path Loss Calculator.
Frequently Asked Questions
What is dBm?
dBm is power expressed in decibels relative to one milliwatt: dBm = 10·log10(P in mW). It is the standard unit across RF because it turns the huge dynamic range of radio power — from a fraction of a nanowatt at a receiver to hundreds of watts at a transmitter — into small, addable numbers, and because gains and losses in dB then simply add and subtract.
What are the numbers worth remembering?
0 dBm = 1 mW, and 30 dBm = 1 W. Every +10 dB multiplies power by ten (10 dBm = 10 mW, 20 dBm = 100 mW), and every +3 dB roughly doubles it. Negative dBm means below a milliwatt: −30 dBm = 1 µW, −90 dBm is a typical faint received signal. Once those anchor points are in your head you can estimate most conversions without a calculator.
How do I convert between dBm and watts?
Power in milliwatts is 10^(dBm/10), and watts are that divided by 1000. Going the other way, dBm = 10·log10(watts × 1000). This tool does both directions: enter a value, pick whether it is dBm, milliwatts, or watts, and it returns all three. Zero or negative watts have no defined dBm (the logarithm runs to minus infinity), which the tool marks rather than inventing a number.
Does this account for legal transmit-power limits?
No. The converter is pure unit maths and knows nothing about regulations. Allowed transmit power — and whether it is specified as conducted power, EIRP, or ERP — depends on your band, region, and license. Always check the limits that apply to you (for example your national regulator's rules for the band) before setting a transmitter's output. This is an educational reference, not regulatory advice.
Unit conversion only — it does not know your band's legal power limits. Check the regulations that apply to you before transmitting. Not regulatory advice.