dBm to Watts Converter — Power Level Conversion
Convert any dBm value to watts, milliwatts and microwatts. dBm is used throughout RF, wireless, audio and fibre-optic engineering to express absolute power on a logarithmic scale.
dBm
Absolute power converted from the dBm value
- 1
Exponent (dBm ÷ 10)
0 ÷ 10 = 0 - 2
Power in milliwatts
10^(0) = 1Every 10 dBm step multiplies power by 10. - 3
Power in watts
1 ÷ 1000 = 0.001000
How does this calculator work?
P(mW) = 10^(dBm/10); P(W) = P(mW)/1000. By definition 0 dBm = 1 mW, 30 dBm = 1 W, −30 dBm = 1 µW. Every 10 dBm step is a 10× power change. Used in RF, wireless, audio and optics wherever absolute power must be expressed compactly over a huge dynamic range.
Formula
How this is calculated
dBm (decibels relative to one milliwatt) expresses absolute power on a logarithmic scale where 0 dBm = 1 mW by definition. Every +10 dBm step multiplies power by 10; every −10 dBm step divides it by 10. So 10 dBm = 10 mW, 20 dBm = 100 mW, 30 dBm = 1 W, and −10 dBm = 0.1 mW.
The conversion formula is P(mW) = 10^(dBm/10). This is the inverse of the dBm definition dBm = 10 × log₁₀(P_mW). Dividing by 1 000 converts milliwatts to watts. Multiplying by 1 000 gives microwatts.
Typical reference values: Wi-Fi access points transmit at 17–23 dBm (50–200 mW); mobile phone transmitters peak around 33 dBm (2 W); GPS satellites radiate at about 27 dBm (500 mW) at the source; a received Wi-Fi signal of −70 dBm corresponds to 0.1 nW. The logarithmic scale is essential because practical power levels span more than 12 orders of magnitude.
Frequently asked questions
0 dBm is exactly 1 milliwatt (1 mW = 0.001 W). This is the reference level by definition. Positive dBm values are above 1 mW; negative dBm values are below 1 mW.
dBm = 10 × log₁₀(P_mW) = 10 × log₁₀(P_W × 1000). For example, 1 W = 1000 mW → dBm = 10 × log₁₀(1000) = 30 dBm.
dB is a dimensionless ratio between two values; dBm is an absolute power level relative to 1 mW. You can add dB gain to a dBm level (e.g., a 10 dBm signal through a +3 dB amplifier gives 13 dBm), but you cannot add two dBm values.
Also known as
TG we-Calculate Editorial Team. (2026). dBm to Watts Converter — Power Level Conversion [Online calculator]. TG we-Calculate. https://we-calculate.com/calculator/dbm-to-watts-calculator
TG we-Calculate Editorial Team. "dBm to Watts Converter — Power Level Conversion." TG we-Calculate. 2026. https://we-calculate.com/calculator/dbm-to-watts-calculator.
TG we-Calculate Editorial Team, "dBm to Watts Converter — Power Level Conversion," TG we-Calculate, 2026. [Online]. Available: https://we-calculate.com/calculator/dbm-to-watts-calculator
@misc{wecalculate_dbm_to_watts_calculator, title = {dBm to Watts Converter — Power Level Conversion}, author = {{TG we-Calculate Editorial Team}}, howpublished = {\url{https://we-calculate.com/calculator/dbm-to-watts-calculator}}, year = {2026}, note = {TG we-Calculate} }
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