dBu (Voltage Level)
dBu = 20 × log10(V / 0.7746V)
Quick answer
This calculator solves dBu = 20 × log10(V / 0.7746V) for Level (dBu). With Voltage 12 V, the result is 23.8 dB. It solves in 2 directions, so you can enter the values you have and get the one you need.
Calculator
Formula
Description
dBu is an absolute voltage measurement referenced to 0.7746V RMS, which is the voltage that produces 1 mW into a 600Ω load. The reference comes from the historical 600Ω impedance standard in telephone systems. Professional audio equipment commonly uses +4 dBu (1.228V RMS) as the nominal operating level, providing higher signal levels than consumer equipment for better noise performance. Despite the historical 600Ω connection, modern dBu measurements are made in a voltage-only context without assuming any specific impedance.
Variables
- dBu — Voltage level referenced to 0.7746V RMS (dB)
- V — RMS voltage (V)
Practical Notes
Professional audio standard is +4 dBu = 1.228V RMS. Microphone levels are typically -60 to -20 dBu. Mixer outputs are designed for +4 dBu nominal with headroom to +20 dBu or more. The "u" stands for "unloaded" (or unterminated), distinguishing it from the older dBm which assumed a 600Ω termination. Most modern audio equipment has high-impedance inputs (10kΩ+), making the 600Ω origin irrelevant.
Symbols and units
| Symbol | Meaning | Default unit | Accepted units |
|---|---|---|---|
| dBu | Level (dBu) | dB | dB |
| V | Voltage | V | pV, nV, µV, mV, V, kV |
Step by step
- 1. What you know: Voltage 12 V
- 2. The relation: dBu = 20 × log10(V / 0.7746V)
- 3. Substitute: V = 12 V
- 4. Result: Level (dBu) = 23.8 dB
Worked examples
Minimum range
Given: Voltage 0.33 V
Result: Level (dBu) = -7.411 dB
Low range
Given: Voltage 3.3 V
Result: Level (dBu) = 12.59 dB
Typical
Given: Voltage 12 V
Result: Level (dBu) = 23.8 dB
High range
Given: Voltage 0.23 kV
Result: Level (dBu) = 49.45 dB
Maximum range
Given: Voltage 2.3 kV
Result: Level (dBu) = 69.45 dB
Solving for each variable
Solve for Level (dBu)
Voltage 0.33 V → -7.411 dB
Solve for Voltage
Level (dBu) 0.3 dB → 0.8018 V
How Level (dBu) changes with Voltage
| Voltage (input) | Level (dBu) (result) |
|---|---|
| 1.2 V | 3.802 dB |
| 3 V | 11.76 dB |
| 6 V | 17.78 dB |
| 9 V | 21.3 dB |
| 12 V | 23.8 dB |
| 18 V | 27.32 dB |
| 24 V | 29.82 dB |
| 48 V | 35.84 dB |
| 84 V | 40.7 dB |
| 120 V | 43.8 dB |
Embed this calculator
Paste this into any page. It keeps working when this page updates, and credits the source.
<iframe src="https://vbatpower.com/embed/dbu/" width="100%" height="460" style="border:1px solid #1f2a37;border-radius:12px" loading="lazy" title="dBu (Voltage Level)"></iframe>
<p><a href="https://vbatpower.com/formulas/dbu/">dBu (Voltage Level)</a> Calculator by vbatpower.com</p>Frequently asked questions
How do you calculate dBu (Voltage Level)?
Use dBu = 20 × log10(V / 0.7746V). With Voltage 12 V, Level (dBu) works out to 23.8 dB.
What is the formula for dBu (Voltage Level)?
The formula is dBu = 20 × log10(V / 0.7746V). dBu is an absolute voltage measurement referenced to 0.7746V RMS, which is the voltage that produces 1 mW into a 600Ω load.
How do you find Voltage when you know the other values?
Rearrange for Voltage: with Level (dBu) 0.3 dB, Voltage is 0.8018 V.
Related Concepts
All Signal & dB formulas →Need more features?
Save calculations, import telemetry data, simulate battery discharge, and collaborate with your team.
Try the App