dBm / dBW / Watt Converter
Convert dBm·dBW·W·mW in one click, with Vrms / Vpp at 50/75Ω.
What it does: Convert between dBm, dBW, and watts, and compute the corresponding RF voltage.
When to use it: When reading transmit power, link budgets, RF module specs, or signal levels.
MEANS This power equals —, corresponding to a sine-wave RMS of — into a — load.
Common cases pre-computed: browse dBm conversion presets →
No history yet. Each calculation is automatically saved to this device.
How to use the dBm converter
Enter a value and unit → pick impedance → read all equivalents.
- 01
Enter a power value
Type a number and pick a unit (dBm / dBW / W / mW). dBm can be negative (sub-milliwatt); W/mW must be positive.
- 02
Pick the load impedance
Used when converting to voltage: RF defaults to 50Ω, video/antenna often use 75Ω, or enter your own.
- 03
Read all equivalents
All four power units plus the Vrms / Vpp at that impedance are given together.
Common power reference
A few handy dBm anchors (including voltage at 50Ω).
| dBm | Power | dBW | Vrms @50Ω |
|---|---|---|---|
| 0 dBm | 1 mW | −30 dBW | 223.6 mV |
| 10 dBm | 10 mW | −20 dBW | 707.1 mV |
| 20 dBm | 100 mW | −10 dBW | 2.236 V |
| 30 dBm | 1 W | 0 dBW | 7.071 V |
| −30 dBm | 1 µW | −60 dBW | 7.07 mV |
dBm is referenced to 1mW; voltage computed for a sine wave into a purely resistive 50Ω.
Common questions, answered in 3 minutes
What is the difference between dBm and dBW?
A constant 30 dB: dBm = dBW + 30 (because 1 W = 1000 mW, and 10·log10(1000)=30).
How many times is each +3 dB / +10 dB?
+3 dB ≈ ×2 (power doubles), +10 dB = ×10. So 23 dBm ≈ 200 mW, 13 dBm ≈ 20 mW.
Does dBm need to know the impedance?
No — dBm expresses power only. Impedance is needed only when you want to convert power to voltage (Vrms/Vpp).
Why is 0 dBm 223.6 mV at 50Ω?
P=1mW=0.001W, Vrms=√(P·Z)=√(0.001·50)=√0.05≈0.2236V. At 75Ω it is about 273.9 mV.
Does the voltage conversion hold for any signal?
Only for a single-frequency sine wave into a purely resistive load. For modulated signals, complex impedance, or a DC component, use the corresponding RMS/impedance model.
Standards and sources referenced by this tool
| Item | Value / Formula | Source |
|---|---|---|
| dBm definition | 10·log10(P/1mW) | Decibel power ratio |
| Voltage conversion | Vrms=√(P·Z) | P = Vrms²/Z (sine, resistive) |
Voltage conversion assumes a single-frequency sine wave into a purely resistive load. No external API.