Audio level converter: dBu, dBV, dBFS, volts
Type a level in any unit. Set your converter's alignment for dBFS.
dBu
–
dBV
–
dBFS
–
Volts RMS
–
Volts peak
–
Volts peak-to-peak
–
How it works
dBu = 20 × log10(V ÷ 0.7746)
dBV = 20 × log10(V ÷ 1.0)
dBFS = dBu − (the dBu level that equals 0 dBFS)
dBV = 20 × log10(V ÷ 1.0)
dBFS = dBu − (the dBu level that equals 0 dBFS)
0 dBu is 0.7746 V RMS: the voltage that puts 1 mW into 600 Ω, kept as a reference after 600 Ω lines went away. 0 dBV is 1 V RMS. So any dBV figure is 2.21 dB higher when you write it in dBu.
dBFS isn't a voltage at all. It's relative to the converter's clip point, so you need to know how the converter is aligned. If 0 dBFS is +24 dBu, then a −18 dBFS meter reading is +6 dBu at the analog output.
+4 dBu vs −10 dBV
| Nominal level | Volts RMS | dBu | dBV |
|---|---|---|---|
| Pro (+4 dBu) | 1.228 | +4.0 | +1.8 |
| Consumer (−10 dBV) | 0.316 | −7.8 | −10.0 |
| Difference | 11.8 dB | ||
That's why the gap is quoted as "about 12 dB", not 14.
Field notes
- Alignments differ. EBU R68 sets 0 dBFS to +18 dBu (alignment tone at −18 dBFS = 0 dBu). SMPTE RP155 puts a +4 dBu reference at −20 dBFS, so 0 dBFS = +24 dBu. Many interfaces and consoles land somewhere between +18 and +24 dBu, and some have a switch. Check the spec sheet for "maximum output level".
- Meters lie about peaks. A VU or RMS meter reading +4 dBu on program can have peaks 10–20 dB higher. Leave the headroom for them.
- Driving consumer gear from a pro output usually just needs about 12 dB of attenuation (a pad or turning the output down), plus attention to balanced-to-unbalanced wiring.
FAQ
Is dBm the same as dBu?
Only into 600 Ω. dBm is power (1 mW reference) and depends on the load. dBu is voltage only, which is what matters on modern bridging inputs.
What's the "u" in dBu?
"Unloaded" or "unterminated": the voltage reference without assuming a 600 Ω load.