Calculators / dBm to Watt

dBm to Watt
Converter

Convert RF power between dBm, Watts, milliwatts, dBW, and microvolts. The go-to tool for RF power calculations, transmitter power conversion, and link budget analysis. Instant bidirectional conversion.

▶ Start Converting 📖 Theory
dBm SCALE −30 0 +10 +20 +30 +40 20 dBm = POWER 100 mW = 0.1000 W = −10.00 dBW = — µV (50 Ω) FORMULA P(W)=10^((dBm−30)/10) P(dBm)=10·log(P_mW) COMMON REFS 0 dBm = 1 mW 30 dBm = 1 W
Power Level 20.0 dBm
−100 dBm+60 dBm

⚙ RF Power Converter

Input in dBm / dBW

Reference: 0 dBm = 1 mW, 30 dBm = 1 W

dBW = dBm − 30

−100 dBm−500+30+60 dBm
⇄ swap

Input in Watts / mW

100 mW = 0.1 W = 20 dBm

dBm Result
20.00dBm
UnitValueNote
dBm—dB ref 1 mW
dBW—dB ref 1 W
Watts (W)—
milliwatts (mW)—
microwatts (µW)—
nanowatts (nW)—
Vrms (into Z₀)—50 Ω
Vpp (into Z₀)—50 Ω
µV rms (into Z₀)—50 Ω

📖 Theory

dBm is a logarithmic unit of power referenced to 1 milliwatt. It is the standard unit for expressing RF power levels in communications and RF engineering.

dBm → Watts

P(W) = 10^((dBm − 30)/10)

Or equivalently: P(mW) = 10^(dBm/10)

Watts → dBm

P(dBm) = 10 · log₁₀(P_mW)
P(dBm) = 10 · log₁₀(P_W) + 30

Voltage (into Z₀)

Vrms = √(P_W × Z₀)
Vpp = Vrms × 2√2

Key Facts

+3 dB → power ×2
−3 dB → power ÷2
+10 dB → power ×10
−10 dB → power ÷10
+30 dBm → 1 W exactly

📊 dBm Power Scale Viewer

Live Scale | ◉ Logarithmic power scale & dBm vs Watts curve
Chart
Power level 20 dBm
−100+60 dBm
dBm Reference Scale +60 +40 +20 0 −30 −50 1 kW 100 W 100 mW 1 mW 1 µW 100 nW 20 dBm CURRENT — — COMMON REFS +50 dBm = 100 W +40 dBm = 10 W +30 dBm = 1 W +20 dBm = 100 mW +10 dBm = 10 mW 0 dBm = 1 mW −10 dBm = 0.1 mW −20 dBm = 10 µW −30 dBm = 1 µW −73 dBm = S9 (ham)
ℹ
RF Power Insights

Enter a dBm or Watts value to see power level context.

Common Applications

📻

RF Power Calculations

Convert transmitter output power between dBm and Watts. Add or subtract gain/loss in dB to calculate signal levels throughout an RF chain.

📡

Transmitter Power

Ham radio transceivers output 5–100 W. WiFi APs output 17–23 dBm. Convert quickly between the two representations used in datasheets.

🔗

Link Budget Analysis

All link budget calculations use dBm so gains and losses can be simply added/subtracted. Convert final result back to Watts for power delivery calculations.

🔬

Test & Measurement

Spectrum analysers and signal generators use dBm. Convert to Watts/Volts when comparing with datasheet specs or connector/cable power ratings.

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