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dBm to Watts Calculator

Convert dBm ⇄ watts, milliwatts and dBW instantly. Built for RF, microwave and 5G/LTE link-budget work — with the exact formula, worked examples and a common power reference table.

⚡ dBm · mW · W · dBW — logarithmic power conversion

Example: 43 dBm ≈ 20 W — a typical macro-cell power per port. 23 dBm ≈ 200 mW — a handset's max uplink.

How it worksThe dBm ⇄ watt formula

The decibel-milliwatt (dBm) is a logarithmic unit: it expresses power as a ratio to 1 milliwatt. To go from dBm to linear power, raise 10 to one-tenth of the dBm value; to go the other way, take the base-10 logarithm and scale by 10.

PmW = 10^(PdBm / 10)    PW = 10^((PdBm − 30) / 10)

PdBm = 10 · log₁₀(PmW) = 10 · log₁₀(PW) + 30

dBW = dBm − 30    (1 W = 30 dBm = 0 dBW = 1000 mW)

The "+30" comes from the 1 W : 1 mW ratio being a factor of 1000 = 10³, i.e. 30 dB. A handy mental shortcut: every +3 dB doubles the power and every +10 dB is ×10. So 43 dBm = 40 dBm + 3 dB = 10 W × 2 = 20 W.

ReferenceCommon RF power levels

dBmdBWPowerTypical use
+46+16≈ 40 WMacro base station (per port)
+43+13≈ 20 WMacro / high-power radio
+40+1010 WHigh-power amplifier
+37+7≈ 5 WMicro / small cell
+3001 WIndoor small cell · CB radio
+23−7≈ 200 mW5G/LTE handset max (power class 3)
+20−10100 mWWi-Fi / Bluetooth class 1
+15−15≈ 32 mWTypical Wi-Fi client
0−301 mWReference level
−30−601 µWStrong received signal
−90−1201 pWGood cell-edge RX level
−110−14010 fWNear RX sensitivity limit

dBm is the everyday unit for transmit power and received signal strength (RSRP/RSSI) in cellular and Wi-Fi systems.

FAQdBm, watt & dBW questions

How do you convert dBm to watts?
Watts = 10^((PdBm − 30) / 10). Equivalently, convert to milliwatts with mW = 10^(PdBm/10) and divide by 1000. Example: 43 dBm → 10^((43−30)/10) = 10^1.3 ≈ 20 W.
How many watts is 30 dBm?
Exactly 1 watt (1000 mW), since 10^((30−30)/10) = 10^0 = 1 W. That makes 30 dBm a useful anchor point: 0 dBW.
How do you convert watts to dBm?
PdBm = 10 · log₁₀(PW) + 30. For example, 5 W → 10·log₁₀(5) + 30 ≈ 37 dBm.
What is the difference between dBm and dBW?
dBm is referenced to 1 mW; dBW is referenced to 1 W. They differ by exactly 30 dB (dBW = dBm − 30), because 1 W is 1000× (30 dB) larger than 1 mW.
What transmit power does a 5G phone use?
A handset (3GPP power class 3) tops out at 23 dBm ≈ 200 mW. Macro base stations run around 43–46 dBm (20–40 W) per port. See the link budget calculator to turn that into coverage.

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