dBm / dBu / dBV Calculator
Convert dBm, dBu, dBV, and dBW to absolute power and voltage values.
Component Values
Results
Audio & RF Reference Levels
| Level | Value | Description |
|---|---|---|
| Line consumer | -10 dBV | -10 dBV — consumer hi-fi, phones |
| Line pro | +4 dBu | +4 dBu — professional audio |
| Mic level | -60 dBu | -60 to -40 dBu — microphone output |
| Full scale | 0 dBFS | 0 dBFS — digital full scale (max ADC) |
| WiFi −30 dBm | -30 dBm | -30 dBm — excellent WiFi signal |
| WiFi −70 dBm | -70 dBm | -70 dBm — fair WiFi signal |
Decibel measurements in audio and RF always have a reference level. dBm is decibels relative to 1 milliwatt — used in RF and telecom. 0 dBm = 1 mW into 50 Ω. dBW is decibels relative to 1 watt. 0 dBW = 1 W = +30 dBm.
Audio engineering uses voltage-referenced decibels. dBV is relative to 1 V RMS. dBu is relative to 0.775 V RMS — a historical artifact from the days when 600 Ω lines were standard and 0 dBu represented 1 mW into 600 Ω. Consumer equipment typically operates at −10 dBV, professional at +4 dBu.
The conversion between dB and absolute values depends on whether you are dealing with power or voltage. Power ratios use 10×log₁₀, voltage ratios use 20×log₁₀. To go from dBm to voltage in a 50 Ω system: first find P = 10^(dBm/10) × 1 mW, then V = √(2 × P × 50).
dBm → Power
P(mW) = 10^(dBm/10)dBV → Voltage
V = 1V × 10^(dBV/20)Key Points
- dBm: power ref. to 1 mW (P = 10^(dBm/10) × 1mW)
- dBV: voltage ref. to 1 V (V = 10^(dBV/20) × 1V)
- dBu: voltage ref. to 0.775 V (V = 10^(dBu/20) × 0.775V)
- +4 dBu = professional audio level ≈ 1.23 V RMS
- −10 dBV = consumer audio level ≈ 316 mV RMS
Applications
- RF link budget calculations
- Audio signal chain level matching
- Wireless receiver sensitivity analysis
- PA and amplifier output power specification
Practical Examples
A 2 V RMS signal expressed relative to the 1 V dBV reference.
dBV = 20·log10(2/1) = +6.02 dBV
10 mW of RF power expressed in dBm (reference: 1 mW).
dBm = 10·log10(10) = +10 dBm
Did you know? dBm (decibels relative to 1 milliwatt) is the universal reference level in RF and microwave engineering. A typical Wi-Fi router transmits at +20 dBm (100 mW). Your phone might receive a signal as weak as −90 dBm (1 picowatt) and still maintain a connection.